Nobody is going to lose anything. UH is threatening to not sell on the exchange, so when UH exchange customers re-up they will just pick a new insurer.
This is actually COMPETITION rearing it's beautiful head. The exchange market is over saturated. Some are making money, some are losing money. Let the winners win and the losers lose. Eventually the right amount of insurers will be selling the right plans.
With the proposed mergers, we'd have three major insurers, down from five. What exactly is the "right number" of insurers, in your mind?