A lot of API nodes currently run HAF. After the next release, I expect all of them will (because new hivemind features are only being added to HAF-based version of hivemind).

Other than general purpose API node operators, anyone who builds a HAF app will need to run a HAF server (because their app will run on it) or else they will need to convince someone else who has a HAF server to run it for them.

We're also building several new HAF apps that will probably encourage more people to want to run a HAF server.