Many questions loom in the second half of the season

— -- The first half of the Sprint Cup season brought some of the closest finishes in NASCAR history, a surprise manufacturer announcement and a delayed farewell tour that still has epic potential.

Denny Hamlin won the Daytona 500 by inches over Martin Truex Jr., Stewart-Haas Racing announced a switch to Ford in 2017 and the team co-owner, Tony Stewart, missed the first eight races of his final Sprint Cup season with a broken back.

With 18 races down and 18 races remaining -- eight Sprint Cup races left in the "regular season" before the 10-week Chase for the Sprint Cup -- the focus won't just remain on the championship battle.

What to watch for over the second half of the season:

Free agency

The top free agents, based on points, are Martin Truex Jr., Ryan Newman, Paul Menard and Kyle Larson.

Truex and Larson more than likely will stay where they are, although until they sign contracts, their teams have to worry that they might be ripe for the picking if something unexpected happens at another team.

Some would think Hendrick Motorsports would want to snap up Larson to replace Kasey Kahne, but Kahne's contract runs through 2018 and support from Great Clips might be too much for Hendrick to want to try to attempt a buyout. And, frankly, the No. 5 team doesn't have the best history. If you're Hendrick, do you wait until Dale Earnhardt Jr. or Jimmie Johnson seems ready to retire before attempting to lure Larson from his current spot at Chip Ganassi Racing? Finally, Hendrick has remained loyal to his drivers in recent years, and he has stuck with them through hard times such as the past couple of years for Kahne.

Newman likely will depend on sponsor Caterpillar's preference but also RCR must want to get Ty Dillon to Cup. Menard also must renew his deal, and with sponsorship, could take it to another organization, but they also would need to buy a charter to be guaranteed spots in the field.

The replacement for Sprint

There seems to be plenty "flavors of the week" and even a few "flavors of the month," but so far no one company has emerged publicly as the solid front-runner to replace Sprint. Walk through the garage and every couple of weeks, a new name surfaces of who will serve as title sponsor for 2017 and beyond.

It's not the greatest sign for NASCAR that it doesn't have the deal done yet, but it also should not cause panic -- with the heavy drop in ratings the first two races before a more manageable decline for many other events, any company taking a serious look would want to wait and see how things developed this season with a new aero package and without Jeff Gordon.

The racing has improved, and while the television and attendance figures raise concern, NASCAR should find a company willing to sponsor the series. It likely needs to get it done at least in principle by the end of August, as companies set their budgets for the upcoming year.

NASCAR has wanted a 10-year deal like the original one signed by Nextel, but it probably can get more annually from a three-year or five-year deal.

The sponsor not only provides the bulk of the $20 million-plus season-ending points fund but also must make a commitment to promote the sport through advertising and other promotions (not to mention NASCAR likely hoping they sponsor the All-Star Race).

Tony Stewart

Stewart has won a race in his final season. He's in the Chase as long as he remains in the top 30 in points and he would have to have a disastrous next eight weeks to drop out.

So now comes the Chase for Stewart's final season. How far can he go?

Stewart will try to replicate his 2011 performance in the Chase where he turned a mediocre season into the championship by winning five of the final 10 races.

That probably won't happen. But are you going to be the one to doubt the three-time champion in his last 10 races with a zero-cares-given attitude?

Hendrick Motorsports

Rick Hendrick celebrated his 67th birthday Wednesday. He might not have had room for any cake considering how fed up he was with his team the past couple of weeks.

Hendrick Motorsports failed to put any of its drivers in the top 10 at Kentucky. The same was true a week earlier at Daytona. It was the first time since October 2011 that Hendrick failed to have a top-10 driver in back-to-back races.

In looking at the past nine races, the Hendrick drivers would rank sixth ( Chase Elliott), 18th (Kasey Kahne), 23rd (Dale Earnhardt Jr.) and 25th (Jimmie Johnson) in the standings.

Should they be worried? Maybe.

The past four races have had little to do with what the drivers will face much of the remainder of the season, as Michigan had the proposed 2017 rules package, followed by a road-course race at Sonoma, the restrictor-plate race at Daytona and another "2017" race at Kentucky.

2017 aerodynamic package

NASCAR hopes to have the 2017 rules to teams in August, or at least the main parts of the rules package so teams -- and Goodyear -- can start working toward 2017.

The race at Michigan appeared as a good start, and the race at Kentucky gave NASCAR a chance to see the package on a newly paved track.

While it might not hurt to get one more race with the 2017 package, NASCAR probably has seen enough to try to implement many of the elements for next year. The key is lowering the corner speed and creating cars where side force is not such a big an issue so that a driver trying to make the pass can't be pinched and lose immediate control.

The Brickyard

After an incredible 100th Indianapolis 500, the Indianapolis Motor Speedway made a big push for renewals. With all that effort, where will the Brickyard 400 sit in the IMS landscape?

The 2015 NASCAR race probably had 20 percent of the crowd of the 2016 Indianapolis 500, and no one expects to match it. But if NASCAR only draws 60,000-70,000 at Indianapolis, is that big enough to have an event? Can NASCAR handle being the second, third and fourth fiddle at Indy?

The races at Indianapolis haven't created the most drama beyond fuel mileage ones. And the Xfinity Series races at Indianapolis will have heat races. That should be, well, gulp, interesting.

Daniel Suarez impact

Daniel Suarez became the first Mexican-born driver to win a NASCAR national series race when he captured the Xfinity Series race victory last month at Michigan.

So what's next?

It is unlikely Suarez will have a spot at Joe Gibbs Racing in a Sprint Cup car. Will someone else give him a chance in the next few years? It probably depends on if he wins again as well as the sponsorship he could bring with him.

And the other question is what will happen to the NASCAR Mexico Series, where Suarez ran before coming to the United States? NASCAR has not released a schedule yet for the series in 2016, and while NASCAR still works to come up with some sort of abbreviated 2016 schedule, time is running out for any races to happen this year.

Donald and Hillary

It's an election year and there are 16 races remaining before the 2016 U.S. presidential election.

Will Donald Trump, BFF of BZF (NASCAR Chairman Brian Z. France), show up at a race? Hillary Clinton? Or their running mates?

Fans don't like it when their sports get political. But with NASCAR races in swing states such as Michigan, New Hampshire, North Carolina, Pennsylvania and Virginia between now and mid-October, it makes NASCAR a likely candidate for candidates.

If they don't make it, locals can still expect others running for federal office or governorships to use NASCAR to meet and greet and ask for votes.

Don't say we didn't warn you.