From my observation, smaller studios are vastly more likely than larger ones to already be in compliance with this initiative's requests: It's not the giant, AAA games that are having community servers or peer-to-peer networking. Companies that are doing that already have to change nothing to be in compliance.

Studios that have private, monopolized backends merely need to release their server binaries at the end of life. That's not a significant expense, either (you already have access to file distribution in order to distribute your client in the first place). Assuming that the studio is paying directly for file distribution (not the case for most), and that the server binaries are 100 GB (an obscene over-estimate), and that every single user downloads the server files, you're looking at a couple of cents or so a user. Which again, smaller studios don't pay for file distribution, that's coming out of the platform fees that you're already paying.

The only hard and fast, "this might cost us money" position I can point to is the large studios that release franchises lose the ability to use cutting off people's access to previous games in a series as a motivator to purchase newer ones in the series. And that's an ability exclusively available to massive studios that put out entire franchises of games.