These platforms are still relatively young. We need to roll the clocks foward another 10-20 years to truly understand what level of control they will be able to exert on public knowledge and speech, either at the behest of their investors or through government pressure.

I wonder whether one solution is for everyone to own a "personal cloud computer" (a relatively cheap VM) on which they install software much like they did in the pre-SaaS era. They might also be able to open up file system and SQL interfaces for certified external providers.

Theoretically, the same arguments that apply to a cloud service provider would apply to a cloud infrastructure provider too, but if the contract were to define the infrastructure as leased property, and all data stored on it as belonging to the user, then it might be somewhat harder to control.