I understand your concern about there not being a big enough leap, but all of those things are possible, flying mounts, etc. Has it been implemented? I don't know, I am sure we'll find out more, but they seem to of made great improvements over the original in image quality, character animation and gameplay mechanics, we've only seen 14 minutes of a carefully selected playthrough.
Are you talking about the leaves/foliage not reacting when Aloy moves through them? in that case, it seems to be limited to smaller foliage, as the tall grass moves when she moves through it.
As far as GT7:
Gran Turismo™ 7 brings you the best features from the history of the franchise. Find your line.
www.playstation.com
That hasn't been updated yet, so the official PlayStation still says PS5, and the video has a PS5 label, more than likely he misspoke during that interview, it happens.