I do not believe the requirement that comes with a day of obligation (Sunday or otherwise) is to somehow go to a unique Mass for that day. The focus of the precept is not to require you to go to a certain minimum number of Masses, it’s to require you to keep holy days holy by having gone to Mass on them. This is why, for instance, when a holy day falls on Sunday, you’re not required to go to two Masses. The requirements don’t pile up; they’re both satisfied by a single Mass.
And it has nothing to do with the abrogation of obligations. If you view the obligation properly (not as having to go to a Mass
for that day, but as having to go to a Mass
on that day) then you’ll see that no abrogation is required. A single Mass simply satisfies both, because, due to the way our liturgical days are delimited, it falls on both days.
The conclusion you draw about the USCCB, also, does not follow, I’m afraid. The USCCB is not generally in charge of telling priests what their Mass schedules must be, and there will obviously be man, many instances in which priests are not able to schedule evening Masses and parishioners are not able to attend them.
That regulation dealt with a slightly different issue, and it’s not clear whether it’s in force anyway in the modern form of the rite. At the
cathedral in Las Vegas, for one, they have an anticipated Mass at 2:30 PM (as well as 4:00, 5:30, and five more times on Sunday).