He should do it and wait for a top team's QB to get injured this fall and walk on the field right out of the broadcasting booth. Or screw it, take another year off. At this point, he isn't holding nearly as many cards as he could, so just holdout until people start dropping their cards.
He does it and pulls it off, assures him a spot in the HOF without question. If not, it'll be the most high-profile failure in the NFL recent memory (excluding major crimes), only other one that probably is even on that radar would be Johnny Football, but that's a completely different scale.