fwiw this is all me Avante style rambling
I don't know what you mean by exposed. A QB who can make plays with his feet's style can't get exposed--it's just an extra weapon the QB has. Injury from running is the only downside. The best dual threat QB was prolly 2010 Vick--and his play itself never really got exposed.
The one read and run guys get exposed because they never make the transition from college to the NFL. Cam was like that at Auburn. Johnny was like that his first year, but actually tried to go through progressions his second. Wilson wasn't. Luck wasn't. RGknee wasn't but played in a "playless" system offense. I don't think you can use this against Football considering that 99% of college QBs don't make it from their college offenses to the NFL ones.
As for durability, I don't know if we even have a whole lot of evidence on that. All of the running QBs who have got their shot have either been the bigger 6'4 dudes or have been athletes masquerading as QBs. Problem with using the bigger guys to compare is that the 6'4 athletic QBs have different issues with injury from where guys have to tackle em. You don't hit Cam like you hit Wilson. You have to Cam's knees/collarbone up to bring him down. The other guys aren't real QBs, no point in talking about them. (Ex: Kordell Stewart)
So who's left? Athletic system QBs. Guys like Akili Smith, Andre Ware, RG3. Cause , even Vick didn't play in a QB friendly offense like all of these guys did.
Akili Smith and Ware flamed out because they were never pro style passers and couldn't make the transition, so not because of injury. If Knee flames out, it'll be because of injury--but Cleveland certainly isn't going to run as much zone read as the Redskins did...
tl;dr
All I've managed to say in all of this is the "no " comment that if Football doesn't pan out, it's not going to be because of injury--it'll be because he's like every other system QB who can't make the transition. It doesn't matter that he ran a lot in college.
Rodgers/Big Ben/Wilson all do it just fine in a sustainable way. What isn't sustainable is 1) Not sliding like Vick 2) read option based offenses.
I think Johnny will slide and try to protect himself, but I don't think he's a NFL ready QB today even though everyone/ESPN wants him to be. He's what, 21 years old? He played in a system offense in college. He was never forced to really go through his progressions and could do stupid hail mary because he had the best safety blanket in CFB.
He should be miles away from being NFL ready tbh.