I guess the proof will be in the pudding – new entrants to mountain biking will take whatever is available, but this was true when only 26″ was available – if veteran MTBers and decent riders feel the need to stick with 26″ then the industry will continue to support it just through economics.
It would be surprising if the whole industry moved away from their bread and butter frame sets for the new vogue, however they all obviously feel that is where the money is (albeit based on the need for everyone to follow the “fashion”).
I think we all agree that there is no perfect wheel size for everyone and the choice of wheel size has always limited (although having said that there were already 20″ 24″ 26″ 29″) so having a new size is undoubtedly a good thing as it gives more choice, the main concern is having change forced upon us (and thereby limiting choice).
I do not believe that we will lose 26″ forever. Yes there will be a smaller range of bikes available in that size but the range is already massive so it can cope with a thinning out.
So change is a good thing and I for one have embraced it by buying a 29er, but my main reason for doing so was that the frame at that wheelsize feels better for my height.
Vive la difference! 😀