If you pull the plug on JP now (and I am sort of on the fence on this one) you will have to live with consequences.
Holcomb is not the answer as he will never lead a team anywhere.
That leaves Nall, who may or may not be the answer. But if you pull Losman for Hall, then that's it for Losman. If Nall can't get it done here's where your at.
Can you find a decent QB in free agency (I don't know who will be available in the off-season), or are you back to another 'project' by drafting another un-proven taelent with 'potential. Are Bills fans ready for another 3-5 year's of hoping this guy is the next Kelly?
Personally I have probably seen enough of Losman, but as I said, if you pull the plug now, you have to be prepared to live with the consequences.