Sony has confirmed that the PS5 will be backward compatible, which means that you will be able to play games that were released for the previous console, the PS4 on the new system. Since Minecraft was available on the PS4, you will be able to play it on the PS5 when it releases for sure.
As for an official release for the PS5, it is hard to say. Microsoft owns the game and since they are also launching a new system, they may decide to work on a version of the game that has improved features to take advantage of the power that the new generation of consoles will have.
The PS5 will have a boost mode to make older games perform better. Similar to what we see with the PS4 pro having a boost mode. Even if there isn’t an official release, the older version of the game will look better on the new console.