Will they trade for Reek or Jefferson?
Which RB(s) are they taking in the draft?
It doesn't matter which RB they take in the draft or sign in FA because they refuse to commit to establishing the run as part of the offense. Until there's a philosophical pivot in that regard, they will always live and die with Mahomes, and as great as he is, the league continues to show that even the greatest QBs can only carry it solo for so long.
The number one thing they need to do is be a more balanced offense. Keep Kareem as the vet and throw the bag at Allgeier or Breece Hall. I had hopes for Pacheco, but it's concerning that he can't outright overtake Hunt (I think part of the reason Pacheco can't overtake him is that KC doesn't commit to the run, and Pacheco seems the type of runner who needs carries to get going).
Whichever one you get, draft a complementary back in the mid-rounds. I'd suggest going for Breece. Allgeier's top motivation will be going somewhere that gives him the backfield to himself, or at least the lion's share. Houston's a good spot for him with Mixon's uncertain future.
As far as WR, they need a high-level possession/chain-mover type that's the "when in doubt" target once Mahomes starts improvising. I'm assuming that's gonna be Rice once Kelce moves on, but then you have to replace Rice with a high-level guy too. They're in this weird gift/curse situation where anybody can have a big game out of nowhere, but as a result, they probably have failed to invest in defining roles for guys, and they don't have the talent to let that fall by the wayside.
Defensively, they need a QB hunter. Other areas of improvement would be nice, but the outright need is a pass rusher.
They've got the QB and are solid defensively. Their pedigree is as good as it gets, so this isn't a rebuild. It's just a reality check.