Epic Games Psyonix

Psyonix, the studio behind one of 2015's biggest games, Rocket League, was just purchased by Epic Games. The acquisition is pretty much set in wet cement at this point, with the final crossing of the t's coming later this Spring.

Yes, this also means that Rocket League is leaving Steam and is now an Epic Games Store exclusive. Those are the long term plans. In the short term, nothing much will change at all. Psyonix gave a rundown of what they say will happen with the game in the coming months.

In the short term, nothing will change at all! We’re still committed to providing Rocket League with frequent updates that have new features, new content, and new ways to play the game for as long as you’ll have us.

In the long-term, we expect to bring Rocket League to the Epic Games store and to leverage our new relationship to grow the game in ways we couldn’t do on our own before. We believe that bringing Rocket League to new audiences with more support is a win for everybody.
So, it will be on Steam still or...? Nope. According to a press release sent out by Epic Games, Rocket League will still be available for purchase on Steam (and most third party retailers) until late 2019. Once "late 2019" rolls around, it will go to the Epic Games Store for new purchases while still supporting the game on both platforms.

"The PC version of Rocket League will come to the Epic Games store in late 2019," Epic said. "In the meantime, it will continue to be available for purchase on Steam; thereafter it will continue to be supported on Steam for all existing purchasers."
To put it clearly: If you own Rocket League on Steam, you can continue to play Rocket League on Steam. The Steam version will continue to get updates same as every other version. However, if you don't own Rocket League yet, there will come a point where the Epic Games Store will be the only place you'll be able to get it.

Oh, and if you are a Linux user, you should probably get Rocket League now before you can no longer even purchase the game for your preferred operating system. See, the Steam version of Rocket League supports Windows, Linux, and OS X. Epic only has a client for Windows and sometimes OS X when it wants to work.

Just something to consider.