I really want Revo to branch out and do something that could really surprise people. His work Shingeki no Kyojin has kind of defined Linked Horizon as a very rock-oriented band, and although this is definitely a big part of Revo's music, he has many sides as a composer and I believe he can actually compose everything very well. He adapts his music all the time and it's always amazing.
Personally, I've always wanted Rose of Versailles, the classic and revolutionary anime/manga series, to get a full-fledged remake and Revo to make its soundtrack. It would show a very refined aspect of his style and he is totally capable of doing it. Also something completely different to what Revo usually does is if he were to work on the Persona series. Shoji Meguro has given it a very distinct musical identity, but based solely from some of Revo's more experimental music with releases like Leviathan, he could make a great soundtrack and can even incorporate his "signature rock" style for the battle themes.
I definitely really enjoyed Bravely Default's soundtrack--it is unquestionably the reason why I have become a Laurant and a part of all of this. It would require him to take a little bit of a break from Sound Horizon (which we've had already and I don't want it to happen again in a good while), but I just would love to hear an instrumental soundtrack from him again. Anime openings require a lot less work so I'd be fine with those too.
I really would love him to pursue some more collabs in the future with artists who I think may fit his style. Dream Port was a huge success in my opinion and I'd love to see more in the same vein in the future.