Exactly. I will be extremely disapointed with Millar if this spans into something that touches everyone. The X-men are a subsidiary of SHIELD now, but as we saw in UFF, those in the subsidiaries do not have access to the Top Secret stuff going on elsewhere. The X-men will not know about this other universe, the Fantastic Four probably will only get a limited time to work on it, because when the Negative Zone stops existing, the bridge between the realities is cut forever.
If Bishop comes through as a seasoned Mutant Member of SHIELD, or something interesting like that which is plausable (in relative terms, we are talking superheroes and alternate dimensions), and then gets cut off from his reality, okay, i can deal with that (maybe he would even be an alternate reality Nick Fury). But he should be the only one who goes across time and space to fight crime. That is his character.
Nathan is a soldier, Bishop is a Cop. Bishop's got more of a mind of his own and would probably want to figure out this other reality. Cable would stay put.
I really hope this doesnt lead to the downfall of the UU. We don't want things to get rediculously complicated, or we'll end up with another 616 with a few variations. I started reading the line for something new... we've seen other realities before. Those who read Exiles see them every few issues. They need to be more original....
But as I said, Im fine for this being contained within F4 (and it would still be a major event, just not a cross-over/mini-series, we're going to have U Iron Man and U Secret/Arrival, we dont need another so quickly, this sort of deal could shape the future of UFF, and that -is- major)