He definitely has a chance. Everytime he's won a marathon he's downplayed his fitness and was an underdog against faster opponents.
Not sure how Meb framed his Boston fitness, but his brother last December/January was very amped up about Meb's fitness, saying it was the best of his life, and getting excited about Meb's upcoming race in Boston. I know that part of that is being his agent and all, but still.
The problem I envision for Meb is having the fire the last 6 months for his NYC prep. I mean Boston was the last thing on his running bucket list, and when I saw him speak a week after his win you could just see the complacency. I'm not saying he hasn't put in good training, I'm just saying I think the spark went out momentarily. I think he will get motivated again to try to make one last Olympic team, if he can stay healthy, but I have low expectations for him this weekend. **disclaimer** I also had low expectations for him in London and I was proven to be quite wrong.