The thing that strikes me is: okay, two "willing developers" - but they need to be actually capable, not just "willing" but "experienced and able" and that lands you at a minimum of $100k per year per engineer. That means this system has a maintenance cost of over $16K per month, if you have to dedicate two engineers full to the maintenance, and of course following the dynamic nature of K8s and all their tooling just to stay in front of all of that.
Also, for only two k8s devops engineers in a 24h-available world, you’re gonna be running them ragged with 12h solo shifts or taking the risk of not staffing overnight. Considering most update and backup jobs kick off at midnight, that’s a huge risk.
If I were putting together a minimum-viable staffing for a 24x7 available cluster with SLAs on RPO and RTO, I’d be recommending much more than two engineers. I’d probably be recommending closer to five: one senior engineer and one junior for the 8-4 shift, a engineer for the 4-12 shift, another engineer for the 12-8 shift, and another junior who straddles the evening and night shifts. For major outages, this still requires on-call time from all of the engineers, and additional staffing may be necessary to offset overtime hours. Given your metric of roughly $8k an engineer, we’d be looking at a cool $40K/month in labour just to approach four or five 9s of availability.
Even worse, this feels like the goal was actually about reclaiming their resumes, not the stack. I expect these two guys to jump ship within a year, leaving the rest of the team trying to take care of an entire ecosystem they didn't build.
