I don't see the controlling aspect materializing, except forcing Ruby Central to build a reliable organizational structure. There are companies that are way more involved in controlling projects. Cloud providers or CDNs that start to sponsor, but after a while lose interest unless specific adjustments are being made.

I doubt there will ever be a run-time dependency of rubygems with Shopify. I would be more alarmed if, say, Microsoft GitHub™, Google, Cloudflare would "step up to safe the project".