When I interviewed at USC I think they said they were going to accept their first dedicated greenville class either next year or year after. I believe it will still only be one school on AMCAS despite the two locations and should essentially double the class size. (Currently you can choose to do all your clinical rotations in greenville if you want)
I wouldn't count on anything for sure though, I remember reading that MUSC is crying foul and claiming there was some less than ethical politics that lead to this. Given that MUSC is regionally a big name and is starting to get some national attention, it does seem incredibly weird for a state with small budgets/population as SC to expand their 3rd tier med school instead of devoting more resources to MUSC.
