I don't think there is a cogent risk that general computing open platforms will go away soon.

PCs can be self-assembled without buying them as an appliance from a specific vendor, and you can at the very least install Linux on them. If you care about Windows, Microsoft is adopting open source more and more, you can have install Ubuntu within Windows right now, I doubt they will change course on software installation.

I do have a Linux box in my home and successfully use it for many tasks. This doesn't mean that I feel that all devices that have a CPU in my home must absolutely run unsigned binaries compiled by me.