Though the cheapest houses on the market may not get much cheaper, more-expensive homes still have further to fall, which will likely slow the broader housing recovery.

The Standard & Poor's/Case-Shiller home-price indexes for October are due on Tuesday morning. Economists estimate the index tracking prices in 20 major cities was down 7.7% from a year ago.

That would mark the smallest year-over-year decline since November 2007, but would also leave prices slightly lower than in September, ending a four-month string of month-to-month improvements. That might cause some anxiety about the housing recovery.

Despite recent signs of a bottom, many observers expect home prices to fall an additional 10% before the bust ends.

A pipeline clogged with future foreclosures is the most-cited reason for such forecasts. Another has to do with the shifting mix of home sales.

So far this year, between a third and half of all sales in any given month have been foreclosures and other "distressed" properties, which have mostly hit lower-priced homes, typically the most available to subprime borrowers. Distressed properties have kept home prices falling, even as the government tax credit has boosted sales.

The worst of the subprime-mortgage defaults has likely passed, most analysts agree. That could explain why low-end homes are decreasing as a percentage of total foreclosures, while middle- and high-end homes are taking bigger shares, according to Zillow.com data.

That shift suggests price declines will prove more pronounced in middle and higher-end housing brackets, which haven't yet fallen as far as the broader market. In San Francisco, high-end prices are down just 25% from their peak, compared with 39% for the broader regional market, according to Case-Shiller data.

Monthly payments for adjustable-rate mortgages, which helped many buyers afford more-expensive homes, could rise next year, either due to payment resets or rising interest rates. That trend threatens more defaults on higher-priced properties, which would weigh on prices.

Further government aid could ease the sting, but may not be enough to offset market fundamentals—it couldn't stop prices from falling this year.