Today during the Ubisoft conference call where they discussed first-quarter 2021-2022 sales, Steam Deck got mentioned.
It's an interesting one, since Ubisoft has pretty much left Steam behind in favour of other stores like the Epic Games Store. The Epic store doesn't support Linux, and Epic currently have no intention to do so. So unless people are expected to manually load up Windows to replace SteamOS, companies like Ubisoft would need to bring their games back to Steam to give users a good experience.
During the conference call that we listened to today, a question was asked about the Steam Deck from one investor.
Ubisoft CEO Yves Guillemot replied to say "We're happy to see Steam Deck coming to the industry, it shows that it continues a flow of very innovative new hardware coming to the market and so we will look and see how big it becomes, but if it's big we will be able to put our games on it."
So in future if the device is a success, and plenty of people keep SteamOS 3 on it, we could see the likes of Ubisoft (and so perhaps other big publishers) ensure their games work nicely on it. Ubisoft actually already has Linux ports of some games, since they currently support Stadia (which uses Debian Linux) so it wouldn't be a huge stretch to bring those builds with some optimizations over to the Steam Deck. However, whether they decide to use native Linux builds they have direct control over, or rely on the Steam Play Proton compatibility layer we just don't know - and only time will tell on how it all goes on that.