If the M-kit includes a V10 (for example sakes), a wider fender, different exhaust. Than its 99.9999% percent no, its like saying can you convert my 525i to a M5.

They might come out with an M-Kit aero package which you can make your X5 look similar to a X5-M M-X5 car. They have similar aftermarket packages like that for the current models.