Currently, IME, the Hilton family hotels listed above (Hampton, anyway) have not had room-based wifi to this point. In order to limit the free wifi to, say, one device per room, they'd first have to move away from the "free" or "general password" model on that score.
This has been done at Hyatt properties that used to simply give elites a password at check-in. Now some properties have moved to a model where elites get the base internet speed for free (w X number of devices allowed), with the option to buy up to a higher speed with X+additional devices allowed.
It'll be interesting to see if the full service Hilton properties move to this model as well.