Yeah, I expect the Vision Driver will have other users, they didn't even touch on half the things it can do.

Has it been hacked for other Providence Cards?

It isn't out yet, Premium Bandai stuff takes a while to come out so we won't know for a while

From looking at what images and the video from Bandai regarding the Vision Driver, it looks like the card slot just has a simple switch that's triggered by sliding the card through. Likely any thin solid object would do. It's the buckle reader that's hackable, same as the Desire Driver.

I’m also guessing the Juuga Driver’s Rider Absorber is hackable, though that’s probably better for the Revice thread.

Who's to bet that Buffa doesn't end up returning in the DGP, but becomes an enemy & siding with the Jyamato?

to be fair it sounds plausible. even at his death he seems to be mad at Geats, as if to say "how is it that you always win and i cannot? why are you better than me wtf?" so maybe he wants revenge and hopes that this time he will win? who knows

Well if it happens, hope Ace will finally explain his motivation. Especially about being reunited with his mother.

Michinaga: I was defeated by a mama's boy all this time?
Ace: You try getting separated from your family and see what it does to you.
Michinaga: That's a bit fucked up.
Ace: Oh, now you get it.

LOL! Probably how it goes haha.