> Communication is still a gigantic issue to overcome. So is managing teams and availability during the work day.

Communication is huge but I can assure you I've worked with teams on the opposite side of the globe asynchronously without issue. The concept of "workday" can be tossed aside if we are thinking 9-5 M-F.

Global teams can adjust schedules and work effectively. I know because I've managed teams like this in very complex software projects and it has worked.