This would lead to a slight timing problem, as there are some paradigm shifts in technology on the horizon. USB 3.0 ports will start appearing on computers in Q4 2009; Intel will have a Centrino 2 platform ready to be rolled out around the same time, along with new processors.
In other words Apple has two choices: Wait until early 2010 before updating the MBP (and this will be a major update), or do an interim update sometime during 2010 to keep sales of the current MBP going. If they were to hold off this interim update until the fall of 2009, that version would be the most short lived Mac ever. So the best timing would be to release a slightly updated MBP line in June... July at the very latest.
So, my guess...
MBP 1.0 > Nov 2008
MBP 1.1 > Jun-Jul 2009
MBP 2.0 > Feb-Mar 2010