If MTH ends up out of business, manufactures like Lionel, Atlas and 3rd Rail will still be around to fill the void. Just think, the volume of trains that MTH sold will now be absorbed by the remaining manufactures.
There will be no shortage of O scale, just look at the latest Lionel catalog.
I also think that if any part of MTH survives, it will be Railking along with DCS.
But DCS can't survive on its own without a sustainable conduit for its product, so it needs Railking or some other derivative of MTH.
Dealers will have plenty to sell between O, HO, N, G and Z.