Gillis hurts but like you said the the rest should be replaceable. I don't think Gillis will be at Towns next fall, my guess is that he ends up back at Hayesville or he transfers to a more football centric school like Murphy or Union. As for McClure, he is a good athlete but he wasn't a QB, he would've been a WR at most schools. At Hayesville he played QB out of necessity but he wasn't very good there. Same kind of applies to Holloway at Andrews, great athlete but not a natural QB. If Andrews would've had somebody else to effectively play QB I doubt he leaves.
Needless to say Andrews is done in hoops with Holloway and now Ellis leaving, I hate that for Andrews, it would've at the very least been their best hoops team since the early 00's team with Baxter and Creasman that was ranked #1 in the state at one point that season I believe. Towns is going to be pretty loaded in hoops now with Ellis coming in but they have no size, ceiling is limited without a big moving in. Plus chemistry may be a problem for them too.
It would have to be at least a little tempting for McTaggart to go to Towns for a year because Towns is probably a state title team in hoops with him on the team but his future is in football and it would make zero sense on that front. If I were his parent I let him play out the year at Hayesville and see what kind of offer sheet he has by next summer, if I were unsatisfied with it then strongly consider a transfer to Christ School or Rabun Gap to get back the year of football he missed with injury plus the senior year.