Square Enix has not ruled out the possibility of a PS4 remaster collection comprising PS3 games Kingdom Hearts 1.5 Final Mix and 2.5 Final Mix.

Kingdom Hearts 3 co-director, Tai Yasue told IGN: "We listen to our fans obviously so we'll see what they think [about a collection] and we'll come to a decision on that."

Source : http://www.ign.com/articles/2016/06/15/e3-2016-square-enix-not-ruling-out-kingdom-hearts-collection-for-ps4

Well here we are. We, as Kingdom Hearts fans, are answering Tai Yasue's call. We WANT a PS4 collection including 1.5 and 2.5. The release of those would achieve something wonderful : The possibility of playing through the entire Kingdom Hearts series main games on one, single, console. This is, for us, a dream come true. Many of us already bought the games on their original platform, then bought them on PS3 for the added value of the Final Mix, and now, we are ready to experience it on PS4, should the games be released on 1080p 60FPS.

Please, hear us out! We want the PS4 collection to happen! Spread the word among other KH fans, because only all together can we make this happen.