Self-Hosted as a Service can also become a big industry. In fact, there are already many providers who are essentially SaaS-ing some opensource solutions. Think of WordPress hosting.
Legal counseling for a trust or will for the hardware and software. Training and on-call support.
The challenge is keeping the tech in line with what the owner intended, staying off the cloud and preserving their values. That could mean anything from staying on legacy Java to maintaining an automated lawnmower written in embedded Tcl.