Guys I'm not sure that you realise that we're talking about GSP the guy being champ 11th times in the UFC, beating the top at their time over and over. How can you count him out and neglect all his former fights, this is like if Mike Tyson took a lay off and came back of course he would get a title shot right away.
There is really two options in this fight:
-GSP is broke and need a fight so he took what he think the easier to him and doesn't give a fuck about the results but the money he get
-GSP really want to win this fight and be a champ in MW.
If the second is right I don't think anyone can count him out I believe Bisping is stronger and has as good cardio as GSP; high enough takedown defense and boxing skills to counter GSP style, BUT GSP do one thing better than any other fighter is to come in fights with the right strategy and tricks.
GSP doesn't like to get hit and I doubt he will come into the rings against the MW champ without being fully prepared to fight him, he's a mastermind after all.
Last thing about the timing of this fight if it happens and he beat Bisping then there is a possible title against Anderson Silva for the biggest MMA fight in the history, I doubt any thing else can motivate him more than that.
If I had any insight I would be willing to bet a lot of money on this fight 15-20 days before it happens as the odds will probably be far from reality.