The harsh reality - throwing a football is not an arm activity, it is an entire body activity. The lost hip mobility will mean that Tua has to learn to spin the bean differently. No one knows what that will mean to him until after he tries. Also, Tua throws across his body a ton. That is going to be a lot harder to do now.
Tua may be able to play at the same level that he has, but he may not. No one knows. But his brain is the thing that is most valuable. His brain does the calculations that translate into passes coming out quickly, and being delivered into places that receivers will be in before they get there. His brain is the difference between him as a QB and other guys with incredible arms. As long as his brain is okay, he is going to be a very good QB.