Although the Joint Center for Housing Studies at Harvard University predicts, at least for now, most middle-aged boomers and older seniors will remodel their homes and stay in them as long as possible—known as "aging in place"—eventually the burdens of dealing with a too-big house and yard become too much.

That's when it's time to move to a smaller, single-level home, or an elevator-accessed unit close to transportation, restaurants and other walkable amenities.

The problem is, that's the sort of housing also coveted by the one demographic cohort that's larger than the boomer generation—those now in their 20s and just entering the housing market.

The center notes that in 2007, one in three households in the 65 to 74 age range reported having moved in the prior decade, and that "if the older baby boomers match this mobility rate, some 3.8 million would downsize their homes over the coming decade, lifting the demand for smaller units."

Of course, if you don't want to compete with your children or grandchildren for that sunny two-bedroom down the street from the Starbucks, you can always opt for an age-restricted community. And these often do have the advantages of nearby services targeted just for seniors on site nearby, like recreation centers, doctor's offices and convenience stores.

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But if you still want to live in a neighborhood where all ages are represented, then perhaps you should start looking now, while it's still a buyer's market.