I've read different things about the severity of his injury. CNS said something like "damange to a ligament", and I read elsewhere it was a torn ACL. Doesn't seem like if he'd torn his ACL he would be able to even be doing what he was doing just a few weeks after surgery.
If it's not that severe he will be right in that mix you've mentioned. If he can't get on the field for pre season camp, I'm sure that would ding the draft stock. Interrior lineman aren't typically a high value position, although every now and then teams target and find great ones.