Honestly, I don't think in that scenario, or even if they joined this year it helps them that significantly. IMO it actually could do the opposite. Both of my brothers graduated from Clemson and I did from USC. **they were always Clemson due to my dad's side of the fam and I was Carolina from my mom's side. I've had this discussion with them, and after I gave them my POV, they agreed with me. Unless in a forced scenario, why would you come?
To my point, they already recruit top 10 year in year our, not being in the SEC, and win against schools like UGA, Bama, FSU, Tenn, etc, all over the country in recruiting on some big name recruits. They have in their back pocket, hey, if we can beat FSU year in year out, you'll have a good shot at a power 5 conference title and an easy road to the CFP. If they come to the SEC, they lose that edge. Yeah, they'll have "we are in the SEC, play against the best" but if they do come, they'll have that card against big 10 schools and other lesser FB programs that are in the ACC, Big 12, etc, and then have to play against Bama, UGA, Tenn, LSU, UF, A&M, Texas, Oklahoma, on a lot more regular basis, resulting in a lot more losses than playing against the lowly ACC teams and no longer be able to talk guys into coming to a school in the middle of no where to have a cheap ride to the CFP.