I plan on getting a Sony a7r soon, yet I have a stable of Hasselblad v-system lenses. One of the great things about the a7r is that because its mirrorless, it has a very short lens mount to sensor distance. Much shorter than a conventional SLR. Because a conventional SLR lens is designed to be mounted further away from the sensor plane, there is plenty of room to fit a conversion mount between the a7r and a conventional lens. Thus the field is wide open for third party manufacturers to make adaptors that allow all sorts of other lenses to be mounted to the Sony, from many other lens manufacturers.
The gold standard in third party adaptors is MetaBones, but there are also other manufactures catering for more esoteric mounting systems.
A friend of mine (Tom) has the a7r, and he has purchased a Kipon adaptor that mates the Hasselblad v-system lenses to the Sony. So, we gave it a try the other day, and here are my first thoughts.