Not convinced there is any plan to bring it to mainline...

In fact, I think in the not too distant future we are going to see a return of the two legs in and out of ATL to cover for the inability of DCI to handle the load... A 717 is equal to 2 50's and an 88 is equal to 2 76'er.

ATL-MGM-ATL is a 50 seater
ATL-AEX-ATL is a 50 seater
ATL-MGM-AEX-MGM-ATL could be done with one 717.

I think they'll up-gauge and hop before the flying comes to mainline...
and why wouldn't they take a stab at 82 seats in the current RJ fleet again... The NC or MEC would not go for it anyway, but I think they'll ask.