Retirement bottom line: Many will have to work until 70

— -- Will the old thirtysomething gang still be showing up for work at seventysomething?

That could be the case if they hope to enjoy a financially secure retirement.

Baby Boomers, with their inheritances, homes, and old-fashioned pensions, may appear to be on track for a solid retirement — but some experts say the forecast for the generation born from 1946 through 1964 isn't necessarily so rosy.

While Boomers are more likely than younger workers to have defined-benefit pension plans and certain other advantages — that's particularly true of older Boomers — many may wind up financially ill-prepared for retirement unless they work longer and save more.

The recent financial crisis took a toll on wealth; inheritances on average won't be that big; traditional pension benefits are phasing out; and many shop-till-you-drop Baby Boomers simply haven't saved enough money to last through retirements that should stretch beyond those of previous generations, economists say.

"The majority of today's retirees are able to afford a decent retirement. However, this group is living in a "golden age" that will fade as Baby Boomers and Generation Xers reach traditional retirement ages in the coming decades," according to an October 2009 report led by Alicia Munnell, director of the Center for Retirement Research at Boston College.

"This gloomy forecast is due to the changing retirement income landscape. Baby Boomers and Generation Xers will be retiring in a substantially different environment than their parents did," the report notes, citing longer life spans and retirements and declining "replacement rates" — retirement income as a percentage of pre-retirement income.

As of 2009, in the wake of the housing and stock market crises, some 51% of households were at risk of being unable to maintain their pre-retirement standard of living at age 65, the authors calculated in their report, "The National Retirement Risk Index: After the Crash." Some 41% of early Boomers, 48% of late Boomers and 56% of Gen Xers were at risk, they said.

The financial crisis, however, can't be blamed for everything.

"They weren't prepared even before the crisis," Munnell told CNBC recently. The report noted that two years earlier, 37% of early Boomer and 43% of late Boomer households were at risk.

"The gist of this whole story is that retirement ages are increasing as people live longer and health care costs rise, and at the same time the retirement system is retracting," says Munnell.

Eligibility for full Social Security Insurance benefits is gradually rising from age 65 to 67, Medicare premiums will account for a bigger chunk of spending, increasing numbers of households will be taxed on their benefits, "and people really don't save on their own," says Munnell.

Some researchers believe most Baby Boomers are indeed wealthy enough to maintain their pre-retirement consumption, says David Wise, an economist at Harvard's Kennedy School of Government. Wise, however, says it's instructive to look at the real financial status of elderly retirees near the end of life.

"When you look at it that way, it doesn't look as favorable," he says.

In a recent study, Wise and two colleagues found that "a substantial fraction of persons die with virtually no financial assets - 46.1% with less than $10,000 - and many of these households also have no housing wealth and rely almost entirely on Social Security benefits for support."