I think this is absolutely correct which is why I believe the days where we can count macOS on having the ability to execute non-sandboxed applications are numbered. I think in hindsight apps that have already made the transition to the App Store (or were designed for it) will be at a tremendous advantage over the ones that either aren't adopting that model or have left it.

Google has an even greater advantage than Apple here because they became fully invested in sandboxing much earlier (the browser).