So I have been mapping out two main themes that would be really cool if the next update featured. The first one is a general ocean update. It would add some deeper oceans in the map , along with adding the coral reef biome and adding sharks as a hostile mob. This theme could also have different marine wild life added such as crabs, lobsters, dolphins, stingray. There could also possibly be visible marine fish and marine wildlife in the water. Not too many though. I thought this would be really cool to have in future minecraft and i think this idea could have some potential.
Now the second Idea will sound kind of silly, but I was thinking of adding an outer space world to minecraft. This world would look kind of like the end, and would be a very cool feature to minecraft. Some things that this theme would hold are aliens as hostile mobs, stars in outer space, planets, shooting stars, ufo's, and much more. This theme of the two I think is the least likely to get implemented into the game, but it still is a pretty cool idea to have :P
If you have any suggestions to add to these idea's tell me and I will edit them in! Please diamond or favorite it helps a lot :D