My guess is X5 ///M price will be below $100k.

Lets take a look at current US prices(base).

335i coupe - $42,200
M3 coupe - $57,850

550i sedan - $60,400
M5 sedan - $85,500

650i coupe - $78,200
M6 coupe - $102,100

X5 4.8i - $56,200
X5 ///M - Your guess.