While watching the latest TG:USA, while they were in the UK for the Morgan bit, how would it be if TG:US and TG:TOS got together for a few beers and a wild drunken night later, popped out a crossover show? What do you think?
Crossovers need to happen for a reason. In the case of TGAUS, the show was launching on a new network with two new presenters, so the networks thought it desirable for the TGUK crew to help out, assure the audience that it was still the same production behind the new faces.
TGUS's producers will probably wait until the 2012-13 season, before trying out a crossover. This will depend on whether they think a Top Gear Live! tour could sell in major US cities.