What stuff would you like to see in Minecraft 1.9?

A "retro" gamemode that is basically a Alpha and Beta Minecraft version that were popular. Except debugged to have the newer textures, better performance, new sound textures, etc.

Blocks: I'd like to see a block that can block water, but be transparent for mobs. It would be cool for underwater building.
Biomes: More sea biomes would be awsome. Like sea volcanoes, coral reefs, even things like wrecked ships with maybe sunken treasure.
Tools: I'd like something like a throwing knife. Stack them up throw 4 or 5 at a mob and pick them back up. The grappling hook mod would also be really cool.
Mobs: more bird like creatures like the bat, and water creatures to. Maybe a creature that is extremely strong that will spawn in caves like a troll or giant or something.
Bosses: I'd just like to see more in general.
Dimesions: Something that makes long transportation easier.

Yeah those things wold be so cool!