The FE primes are OUTSTANDING.
However with the A7r designed mainly for static subjects like landscape, I'd bet the majority of users would want a good zoom....
If this zoom is as sharp as say, the Canon 24-70/2.8 mk 2, sony will have a winning combo on their hands.
If this lens is a bit of a flop like the e mount 16-70 zeiss, it will really hurt sales of A7(r)...