Personally, I'd rather see it include other characters. I'd hate if it meant exclusively Ultimates readers are left out of the loop, so I'd like to see it self-contaned plot-wise (ie. even if cap was really mystique, and which i doubt, have her introduced in a way that she becomes an ultimates villain as well as her role in x-men), but I would like to see some other characters.
Not because I like Spider-man or so Wolverine is officially in every series ever written, but because it might mean a huge shake-up of the ultimates. Maybe hawkeye is dead or incapacitated, maybe cap has been a bad guy all along, or one of the other ultimates is the traitor. With thor imprisoned, hulk on some island somewhere, and giant man off the team, that leaves Iron Man + Black Widow, the wasp, and Wanda and Pietro. If some big attack comes they'll need all the help they can get.
If there are no other superheroes, that tells me cap is good, and there is no traitor (unless its one of the weaker members of the team), thor is coming back, and hawkeye is fine. I'm OK with that, as long as we don't go back to the status quo and pretend the last few issues never happened.
I seem to be the only one here who feels this way, but I think The Ultimates is in need of a shake-up. I'm tired of seeing them fight themselves. In 20 issues they've only had one fight that wasn't against a team member, iirc. I'd be glad to see some of them switch sides, a couple more die or quit, and the rest have to have their sorry selves saved by some "less official" superheroes.
However, if it's well written I'll be happy either way. I guess you don't need character changes to fix a story if you have good writing.