Seven Pines may never happen but if some battle does occur and Joe fall wounded then its clear what would happen. G.W. Smith would get command then when he prove unsuitable he waould be replaced by Bragg.
GW Smith became ill after Seven Pines and was out of service until late August that year. I've never read what the illness was, but I'll assume for the moment it still happens.
I have to admit that I had failed to consider Bragg. He was busy in 1862, but he certainly could have been transferred. He had a penchant for fighting subordinates as much as he fought the Union, and his track record in both cases was lackluster (except for Chickamauga the following year), so I think this would have gone badly for the CSA. But Davis did seem to like him.
EDIT: I was pondering Bragg so much I forgot to say this: I do think Beauregard gets the position, at least until he manages to aggravate Davis more than Davis will tolerate ("his to lose," I said

) With Lee sitting, Joe Johnston wounded and AS Johnston dead (by then), only Cooper outranked him. And Cooper apparently never held a field command the entire war.