The reason this makes sense, at least for Github, is because the only valid reason to run your own action runners is compliance. And if you are doing it for compliance, price doesn't really matter. You don't really have a choice.
If you've been running your runners on your own infra for cost reasons, you're not really that interesting to the Github business.
Github runners are slow. We're using WarpBuild and they are still cheaper per-minute, even with all the changes Github has made. Then there's the fact that the machines are faster, so we are using fewer minutes.
There are multiple competitors in this space. If you are (or were) paying for Github runners for any reason, you really shouldn't be.
We also use WarpBuild and very happy with the performance gain. This changes nothing except maybe it should signal to WarpBuild to start supporting other providers than Github. We are clearly entering the enshitiffication phase of Github.
Maybe if everything you use is public-cloud-deployed.
Self-hosted runners help bridge the gap with on-prem servers, since you can pop a runner VM inside your infra and give it the connectivity/permissions to do deployments.
This announcement pisses me off, because it's not something related to abuse/recouping cost, since they could impose limits on free plans or whatever.
This will definitely influence me to ensure all builds/deployments are fully bash/powershell scripted without GH Action-specific steps. Actions are a bit of a dumpster fire anyway, so maybe I'll just go back to TeamCity like I used before Actions.
If you've been running your runners on your own infra for cost reasons, you're not really that interesting to the Github business.