I hope the E+ (except ELR) goes away on the new United. Otherwise my concern would be that EUA puts you in E+ (not F) except GS/1K get E+ automatically.

DL is basically going back to three class of service. I assume they will sell E+ as a separate class as well. UA charges extra for non-elites.

Also UA/ CO will likely align their fleets:

319 & 73G 12F
320 & 738 16F for all of them
739 20F

No E+. Except E+ on 752, 762, 764, 777