CAL4M1TY on 14 March 2009
I'm going to say no.
They've said it's time to worry about the 360 lineup ever since Halo 3 launched, and look how that's gone thus far.
Microsoft is a smart company, it didn't surge past Sony with pure luck. Well timed exclusives and price cuts ensured that it stayed ahead of the big black box thus far, I doubt they'd forfeit their position now (with the PS3 potentially entering it's best year, depending on what does or does not get released in 09 of course).
