They could do that now if they wanted. It wouldn't matter because they'd have a massive network of only their nodes running a fork of bitcoin. As long as we're running our nodes for our bitcoin transactions, it doesn't matter.
Discussion
The question then is if they would be able to have the timechain with more hashing power or not. If yes it will be centralized and without freedom and all development would leave, at least good and open source development. They will probably try something like that, in partnership with some big miners. I still think that promoting more node runners is essentially a good thing and it must be as cheapest as possible, because besides hardware there's also internet GB costs. In Europe it's possible to run a node on a 4G router, but not everywhere.