If you go off just last year's teams at 4A and 321A regionals and their 24-25 counts, it looks as if Nemaha Central and Larned had increases to move up and Cheney and Chaparral would move down. Split would be at 236 & 235 with Silver Lake (236) staying at 4A and Cheney (235) being the largest 321A school.
Of course, that would change if some of the co-op's last year aren't co-opting this year along with any possible new teams.