I think it's more simple than like, making a claim that specific types of QB's have shorter careers. Really, it's just QB's who get hit a lot probably shorten their career - unless they're really, really good at passing. Roethlisberger is main person who comes to mind when I type that sentence. It's pretty absurd how long that guy has played, at the level he has, taking as many hits as he has. Going into this year, he was on pace to be the most hit QB in history. In fact, the most hit QB's of all time are Farve, Elway and Roethlisberger. I mean, Ben is a rollin' out """"backyard football"""" kind of guy, but he's not a running QB lol.
Running could open you up to a few more hits, unless you're really good at avoiding hits - like Jackson is. I'm gonna guess his loss of athleticism will be gradual, and he'll notice. It will be gradual enough that he'll understand that he needs to improve his pocket game, if he hasn't by that point. I bet he will. If he doesn't, then maybe he'll be out of the league earlier? than most? I dunno.
Scrambling quarterbacks (Like Rodgers and Mahomes, people who like to let plays develop), and extremely athletic true dual-threat QB's are not only nothing new, but the league has understood how to maintain these players better. I think because of RG3, you'll never see a coach mismanage the health of their QB the way Shanahan did. Even the effing team doctor said he shouldn't have played - who generally have a reputation for underplaying injuries.
Vick didn't give af. Jackson seems to, by most accounts and measures, to be a dedicated individual. I hate him because he's a Raven. But beyond that, he's awesome.