I wonder how much genetic work over the years has really become so "normal" that we don't even appreciate it anymore. For instance, we often talk about selecting for "gentleness" "lower tendency to swarm" and "production".
These are things that people have been selecting for for 200 years (or more). And if I think about it, I've got to wonder if it's something I really need to worry about so much. I have NEVER seen a hot hive. Never. The ones you read about that go after a guy and chase him 100 yards to his truck? Never seen it. I have also never seen a hive that swarmed a ton. Never. I've seen plenty of variation in production, but I've seen as much in weather too...
Now this is not to say that these "bad" colonies are not out there - but I suggest that they are very much in the minority. And when you read Brother Adam's account of traveling the world to investigate different bee races, you quickly learn that there are some pretty nasty, swarmy bees out there.
All that to say, that I feel that all the breeding and selection has given us a pretty range of bees to work with, and two generations doesn't lose an ounce of it.
So if enough of us put our noses to it, I feel pretty confident we could get to a place where mite resistance was every bit as "normal" to our bees as the traits we have come to expect in our bees to this point.