I truly hope that any company content that is for groups can be done with people in different companies. I would like to do any such content with my LS, but I also really want to join the Gridania company. And if we all have to join the same company to play together . . . well . . . I think my LS is more likely to decide to relocate to WoW than they are to join the Gridania company.

And I suspect that if LS's have to collectively decide on which company to join together, there will be very few joining Gridania's company and many people that would have joined it otherwise won't. While most people can deal with Ul'dah, and I don't know anyone that can't stand Limsa Lominsa, some people just hate the Black Shroud (and tend to be rather vocal about it). ;_;