I think by far the most significant impact is to slash UA's liability sheet for occasional travelers who signed up for UA MP but do not fly often enough to pay attention to a CC or really make it worth it. Mileage earning is going down 40% for this class (100% if flying BE), and with no expiration I think the carried liability is somewhat significant for UA, especially this probably represents a significant number of customers.

Heck, that's me now - I still fly UA once or twice a year when it makes sense for price and schedule, but it's not worth trying to get a UA CC for that kind of travel and I don't really count or care about my miles (I would fly UA on these routes even with no FFP). So UA slashes my earnings by 40% and I keep flying occasionally.