Well, I can 100% feel your concern. We're not there yet and I'm able to operate as per norm on 10.13.x (aside from some performance glitches with 10.13.3+). I will never accept SIP or Gatekeeper. Period. Fortunately I can turn them off, but as soon as I can't... I'm gone or will be sticking with the last version that does and then put my support behind Linux efforts.
Linux UI and app support isn't there yet. There is a Linux project that I'm quite keen of at the moment, but won't mention here, that could make all the difference in the world for us. We definitely need to be able to run our os x apps in other green pastures when the time comes and I believe we will from the way things are going.
Apple's definitely losing it's way right now. I've been told by internals that Apple doesn't truly care about macOS anymore, it's really all about iOS and mobile devices - that's their bread and butter.
But yes, if we are to have real options lined up for when Apple goes completely south, the movement has to grow well past the hackintosh movement. It can all be done, but the lack of unity and fragmentation in the Linux and Unix communities in general have completely screwed things up over the last 20 years.