Depends. The ps3 will perform stronger during the start of 2009 than it has during any other year, because $299 makes a big difference. Just look at its effects this holiday season. Not only that, but the ps3 will have God of War to help it along in North America, and Gran Turismo to help it along worldwide, and they're just two games amongst the ps3's best exclusive line up yet.
The ps3 has everything going for it over the first 2/3rds of next year, and that'll ensure that it at least matches its 2009 total sales in the end.
What matters most, however, is the holiday season. Unless Sony drops the price to $249 or pulls off an amazing holiday line up, they'll be down at least 10-15% year on year much like the 360 was this year, which will keep them from topping 14 million. A price drop is very unlikely, as is a stellar line up. They'll have great titles to be sure (the Last Guardian will in all likelihood be many people's game of the year), but they won't have anything like Gran Turismo or Halo.
There is, of course, and unknown quantity in Sony's remotes. They may actually be somewhat successful, which could impact the ps3's sales in the latter half of the year. At worst they'll do nothing.