Within the KC metro, yes.
If the Royals moved out of the KC area, I'd probably lose most of my interest in them (and currently that's not much anyway). I wasn't die hard by any means, but I watched them a fair amount before their success in 2014/2015, went to several games per year, bought a small game pack in 2014... a big part of those runs were being in KC at the time, going to playoff games for the first time, seeing the city go nuts. If that happened again in a different city? Meh... I wouldn't travel to see them or go out of my way to watch them.
If Mahomes' Chiefs left town, I'd probably follow him... it would be really weird and no idea if I'd feel the same going into playoff games or how I'd feel if they won a SB for another city... but he'd definitely keep me watching. Depends exactly where, but I might even travel for playoff games.
I'm already thinking I'll be done with the NFL after Mahomes (or at least go back to only watching the conference championship games and SB) unless the Chiefs seamlessly move onto another franchise QB, so moving to a different city might actually make for a nice clean (but sad) break if it was after Mahomes retired.