Remember, it's not just the NFL that has its doubts. A healthy third year Adrian Martinez was replaced with a Freshman by his own coach just a few months ago. Frost was looking for someone to execute more quickly and decisively, bring a little more energy. So will the NFL.
I think Martinez responded really well to the demotion, and I'm feeling good about him getting super-focused to have the best season of his career. The NFL is obviously possible, but if I had to put real money on it, I'd say no. Tanner Lee is just an example of what the NFL is willing to overlook if you're a pocket passer of a certain height.
Adrian still checks a lot of the wrong buttons. I think pro teams are willing to build an offense around super talented QBs who bring high mobility to their game, but they have to be outstanding passers with great field vision like Mahomes, Josh Allen, Kylar Murray, and Russell Wilson. They're much less interested these days in the traditional dual threat QB, and won't go out of their way for a QB who runs better than he passes.
It's not really a knock to say Martinez faces the same NFL likelihood as Tommy Armstrong, Taylor Martinez, Eric Crouch, Scott Frost, Tommie Frazier, or Turner Gill. Nebraska really doesn't recruit or develop pro-style quarterbacks.