What no one seemed to realize when they abolished plateau bonuses was that for those of us who fly more than 100000 miles, there is no longer any incentive to continue to fly United after the 100K level is reached. It used to be that there were additional plateau bonuses after 100000, but no more.

Since I will easily fly 150000 miles this year, I'll do the extra 50000 on American and achieve platinum status. I'll still get all the perks I would if I stayed with UA.