A MW mmo sounds cool in theory, but I think it'd be pretty shit in practice. Now, small scale competitive campaigns would be cool, and small scale unit to unit combat is actually the norm once you get outside the Inner Sphere and into Clan territories, but you don't need a full-fledged MMO to do that. In fact, persistent worlds make that kind of thing worse; do you want guys going AFK in the middle of push into Jade Falcon territory? Because if people are grinding away to get a hold of a shiny new PPC rather than feeling accountable to their sibko and pursuing a blood name, it will happen.