Unless United is paying for upgraded service, it will be nothing but a seat. Since United is cheap, I would guess no upgrade on service. Horizon is all first class, but at a coach price. Free beer/wine to all, leather seats and a Wall Street Journal in the morning. Now that's service.
United has more important things to worry about than upgrading service on it's RJs. And don't use the frequent flier excuse, the RJ
's fly short enough segments, and there is still some service. United would have to pay for upgraded service across the board for UAX operators. That's six airlines and god knows how many flights....it wouldn't be cost effective to do.