Lots of games that initially resisted being on Steam managed to find their way on to Steam eventually. For example, Umamusume, Overwatch, Blue Archive, Granblue Fantasy, Apex Legends, Maple Story, Honkai Impact 3rd, Magic the Gathering Arena, Wuthering Waves, Diablo IV, Grand Theft Auto V, Death Stranding, God of War Ragnarok, Dwarf Fortress, Final Fantasy XIV, Honor of Kings, Sifu, Destiny 2, The Sims 3, and many more.
Which other games currently not on Steam will get a Steam release in the near future?
1,000Remasters and rereleases that are sufficiently close to the original game will count for this market, based on my own judgement. Remakes and similar that drastically change games will not count. I'm aware this is vague and arbitrary so here are some examples to get a feel for my reasoning, feel free to ask about any others too.
Examples of games that change things but would still count in my estimation include Steam releases of Final Fantasy Tactics: The Ivalice Chronicles (ground up remake, but strong attempt to be faithful via including classic mode), Dwarf Fortress (original ASCII graphics are included), MvC Fighting Collection Arcade Classics (lots of added features but core games are also sufficiently 'there' without having had stuff replaced).
Examples of games that would not count (if the originals weren't already on Steam) in my estimation include steam releases of Trails in the Sky 1st Chapter (drastically different graphics etc.), Dragon Quest 1+2 HD-2D Remake (drastically different graphically), The Talos Principle: Reawakened (drastically different graphically), Metal Gear Solid Delta: Snake Eater (drastically different graphically), Persona 3 Reload. A port of Demon's Souls 2020 to Steam wouldn't count as a Demon's Souls 2009 release because of how different the graphics are.