Shaft drive is not a new technology and has not met with overwhelming success as it does add a lot of weight to a bicycle and there have been some design issues with Dynamic's shaft driven bicycles.

Have driven a Dynamic with an 8 speed IGH and found it to be quite pleasant but by no means quick... the shaft drive is not as efficient or as light as a chain but does work well in many applications.

Belt drives on the other hand are going to get more and more popular and they go along nicely with the resurgence in popularity of internal gear hubs which I do expect to replace derailleur drives on all but high performance / racing bicycles..