It does indeed seem possible that in the long run we'll end up with one kind of stuff, either from the reduction of logic to physics, or the reduction of physics to math. It's also worth noting that my present model does have magical-reality-fluid in it, and it's conceivable that this will end up not being reduced. But the actual argument is something along the lines of, "We got it down to two crisp things, and all the proposals for three don't have the crisp nature of the two."