Desert looks to be there, them machines i guess drills or somit is in the trailer which was seen near the desert part of gta:sa im guessing its there in full just not seen due to time limits in the trailer and somit to keep ppl guessing probably.
The military was hinted at in the 4chan thing which probably means the military base in the desert again.
anticonscience, well their wasnt a real 3D London game for gta but gta 1 in 2d has had a gta:london expansion pack of sorts.
Whilst i agree it be nice to have a new location such as london for a possible spin on The Italian Job from the 60s film with M Caine in I am please that they will return to a much loved SA map/setting.