I like the idea of turning the "Team system" into a "real guild system".
Somewhere was the idea of an guild bank, which I liked, but this idea puts it all together!
A nice hide out to chill, a new massive money sink (I'd propose to have a big initial fee plus monthly fees, both varying in amout depending on the member size of the team), and a place for future "guild updates".
Every time our team announces winners to some internal event, we search a different place to take a screenshot of that. That sucks! Nice Team house would come in handy here!
PS sry 4 bad english