Renter Nation? Don’t bet on it.

The surge in interest in all things rental has some convinced there is a permanent shift, away from homeownership to a country where apartment living is king.

And looking at the flood of proposals for new rental projects across Massachusetts, one could be forgiven for falling for this notion.

There are thousands of new apartment units in the pipeline in Boston and across the state, with new condo construction seemingly all but extinct.

But for developers who must ride market trends and not be rolled by them, buying into this hype could prove catastrophic.

The numbers don’t tell the whole story here. In fact, much of this interest in the rental market is superficial, with smart developers already eyeing the day when they will be able to convert apartments over to more lucrative condos.

“It’s going to keep going and it’s going to get overbuilt,” warned Tom Skahen, partner and co-founder of Littleton-based PrimeTime Communities, which tracks construction of apartments and condos.

Certainly there are reasons to be bullish, in the short-term, about the rental market.

Boston Rents Rising

Rental prices are relentlessly rising, both here in Massachusetts and across the country.

Boston area rents have risen 2 percent over the past year, to a median of $1,834 a month, Zillow.com reports. By contrast, the median home price in Massachusetts fell 3.7 percent in January 2012 over the same month the year before, down to $260,000, according to The Warren Group.

Moreover, it’s a tight market as well, with occupancy rates in some suburban markets as high as 95 percent, Skahen said.

Developers are responding, with plans for everything from a new rental sky-rise in Boston to major suburban rental complexes in Woburn and Hopkinton and Hudson.

But along with responding to demand, residential developers are also responding to supply – the supply of money that is.

Few banks now will lend on new condo projects, but if you are pitching a rental project, lenders are ready to open their vaults.

“If you have a multifamily rental project, you can get financing all day long,” Skahen said.

Lending Imbalance

The result of this lending imbalance – no money for condos, but a green light for rentals – will soon lead to an imbalance in the market over the next few years.

If all the new apartments in the pipeline get built as planned, we will be faced with a rental glut – just as home and condos sales start to take off again.

Savvy developers can already see this coming and are getting ready to deal with it, Skahen notes.

He is working with one developer, for example, who is including three bedrooms in his rental project on the theory the larger units will fetch healthy prices as condos.

“I know developers who are building multifamily rentals and are planning to convert them three or four years down the line,” he said.

For make no mistake, interest in homeownership is not a thing of the past, it is just temporarily on hold.

No doubt about it, far more renters joined the market over the past few years than new homeowners, and it’s not just a product of the foreclosure crisis.

Young couples and others in the late 20s and early 30s are sitting on the fence, scared off from taking the plunge into ownership by gyrating home prices.

Yet survey after survey shows that most Americans still dream of owning, not renting.

In fact, there are already signs that buyers are starting edge back into the market, with pending home sales having risen for 10 straight months in Massachusetts, according to the Massachusetts Association of Realtors.

And as buyers come back, developers will surely start converting units to condos – if they were smart enough to plan ahead for the switch.

Condo Shortage Looming

While banks may still be skittish about lending on new condo projects, there is a shortage looming, especially in downtown Boston.

That may seem incredible, given that just a couple years ago it seemed like we were overrun with half-empty condo towers.

But there are just 200 unsold units left among the big downtown Boston towers, while even Natick’s Nouveau is now sold out.

As the apartment market gets glutted with new rental units, developers must be ready to make the shift.

“They will be fine in 2012, but if they are building multifamily rentals in 2013 and 2014, I’d be starting to get a little nervous,” Skahen said.