Having a core library of decent games (not necessarily AAA) would help I feel. With Windows some of the earliest games developed are still playable on the latest operating system, which is not the case for Apple who have moved from PowerPC -> Intel -> ARM and each time games developed for the previous architecture have been left by the wayside.
There are actually some great games on the Mac App Store, like Metro, BioShock, Civilization, etc. They are a little old, but the are still very playable and they were expensive to purchase. Depending on how these games were ported, it might not be so simple to recompile them to native AS, and developers are unlikely to want to make the effort for older games where its less likely they will see a reasonable return on their investment.
I think a great approach would be for Apple to pick some of these games, like for example the Metro series, and fund their conversion with the developers with the agreement that these games would then become available in Apple Arcade for a period of time. This could end up benefiting everyone as the library of games will grow, and developers will see renewed interest in their games and Apple will bring a few more people into their ecosystem.