Give it two years and the fairly old Sony chip at the heart of the current models will be retired, and all MF cameras will be at least 100MP.
Even if all new cameras are 100MP (unlikely), I doubt that many MF users will be 100MP.
I own both a 50MP 35mm camera and a 50MP MF. If the the 50MP MF was out first I never would have bought the 50MP 35mm. There is no comparison.
There have been 50MP 35mm DSLR now for a long time. Today not all 35mm are 50MP, in fact very few.
I have a 50MP DSLR and the next one will probably be 30MP or less. Large MP on relatively small sensors is not necessary and is sometimes a disadvantage. The people who buy on widget numbers with lots of money will buy but most won't see the value. In comparison to MF cameras, 35mm are disposable.
I don't think that there will be many people who will discard a 50MP MF camera because they need 100MP. My last H4D was about 8 years old and still working fine. The X1D was an opportunity to go new with very little cash out.
I understand that the total camera market is about 1,000,000 units per month. Of those, only 13% are not Canon. Nikon or Sony. So that leaves 130,000 for all the rest. I would be very surprised if 5% of those were Medium format, so maybe 8000 per month total. That is a very tiny market to compete in.