If you're a Linux gamer who prefers Ubuntu, you might want to look for another distribution in the near future. Valve is dropping official support for Ubuntu in Steam as of the operating system's upcoming 19.10 release, which will cut 32-bit x86 components. The Steam crew aims to "minimize breakage" for existing Ubuntu users, according to Valve's Pierre-Loup Griffais, but it'll shift its attention to another distribution in the future.
As you might imagine, this could create compatibility problems going forward. Even if things don't break right away, there's no guarantee that Steam or specific games will run properly. The cutoff may cause problems for other game platforms, too. Phoronix noted that Canonical's Alan Pope had problems playing GOG titles under Ubuntu 19.10 without the 32-bit packages.
Things might improve in the long run. However, there isn't much time when Canonical is expected to freeze feature development for 19.10 in August. Unless the Ubuntu team changes course, some Linux users might deal with headaches across their gaming libraries -- especially if they're dependent on Steam.
Ubuntu 19.10 and future releases will not be officially supported by Steam or recommended to our users. We will evaluate ways to minimize breakage for existing users, but will also switch our focus to a different distribution, currently TBD.— Pierre-Loup Griffais (@Plagman2) June 22, 2019