I'm not sure how you could come to that conclusion. Fulky hasn't contributed much all year, and yes losing KC is big, but you return literally everyone else off of a Top-4 (maybe higher) SEC finish. I can't imagine how good Santi and James could get after another year elevating their game.
The 3 teams you listed are going to lose way more than we will. Arkansas has 5 seniors on their roster, and three of those are their biggest contributors (Stanley Umude, Chris Lykes, J.D. Notae). Kentucky will lose a ton of pieces to the draft. Auburn is going to lose Jabari Smith and Walker Kessler, possibly Allen Flannigan, and two senior role-players.
We would very likely be the favorite in the pre-season next year if we were to only lose KC, and at worst 2nd or 3rd pre-season in the SEC.