I think it's pretty unlikely that the 5.0 V10 will find it's way into the E70. I think BMW have publicly said that there won't be a proper M version on the X5 but more liley one that has been "breathed on" like the old 4.8is. I think the V10 (or versions of it) will be reserved for full M cars. M cars are as much about handling as power and I think BMW may feel that an M version of the X5 dilutes that ethos. Maybe that will change with the X6.