The tweet is so vague (and devoid of anything remotely resembling confirmation),
that we can't tell if Jeb means regular grass or tall grass.
In the former case, it would grow back on its own.
I recall installing a tall tall grass growth mod and it was pretty overwhelming, Basically after a few minecraft days every grass tile was covered with tall grass. Hopefully it is just the normal green top tile. Still it's kinda counter-intuitive that grazing animals would ignore tall grass and prefer very short difficult to remove grass. But the later would be an easier mechanic to implement i think.
I actually like the new stuff. I meant that the game LOOKED better, visually.
it looked more ALIVE i guess is the best way to describe it. and all the grass was Sooooo much greener, and the trees as well. try compareing screenshots of grass and leaves in alhpa and grass and trees in beta