I don’t believe Maya and Max are ever going to be merged. Those are fire and water different applications, both the code and architecture. I can’t imagine “merging” their code base could produce anything upgrade worthy, not talking about the ‘new killer application’.
A bit more realistic situation is that one package is going to replace the other. Before the last version of the victim they might try to implement most important features of the other package, some scene converters, try to make an easy transition, etc. But I don’t see this making users of the discontinued application being too happy.
All in all the merge option seems very bizarre to me. Both Maya and Max have huge user bases, both cows bring a lot of milk to the farm, why killing one of them? We just have to wait and see, I personally don’t see Maya going from market in less than 4 - 5 years.