"Generally" a hive that obsconds in fall (no bees in it come spring) is a result of high mite count. Been there, done that.
Not all hot hives need a new queen. A skunk messing with your hive will make them "HOT" as well. This usually happens to the outer hives. Always look for skunk activity when dealing with a hot hive.
I've done walk away splits and grafted queens in the past. I've gone to just letting my best hives get a little cramped, then harvest the swarm cells. Swarm cells make some of the best queens I've found. No need to overcomplicate it.
We had (and are still having) a hard winter up here. I suspected a heavier loss than I am seeing so far (not out of the woods, yet). Think I'm probably at a 15 % loss out of 70 hives...which is good for this far north. I will contribute this lack of loss to the extended release Oxalic acid sponge method that Randy Oliver promotes (along with my normal mite treatment).
Bees are like barn cats: You start with a couple, then before you know it, you have far more than you want to deal with and you keep looking for people to give them away to. Might as well keep building boxes.
One of the answers to making a profit with bees is to never buy them but to make your own. Go into winter heavy, knowing you'll lose a few.
I had 8 hive in that yard. Wouldn't the other have mite issues if one was so bad they left since they interact so much? The rest of them are nearly busting at the seems with bees.
The only bees I have purchased have been queens. I have also harvest queen cells. Lucked out doing an inspection and caught them hatching. Got 4 out of that.
My largest issue is time. I'm away from home working so much I don't get to my inspections as often as I should. I loose queens every spring after seeing the hives are doing great like they are now. In 3 weeks or less I will have queen loses. It seem to coincide with crop spraying. I don't catch it and end up with laying workers.
Those two hives were hot last summer as well. Could hardly feed them without getting stung.