Some people (UltraChen, I think) have noted that SFV Ryu in V-trigger can use fireball charging to stagger fireballs, making opponents land on a fireball they expected to clear. I find that Jago can already stagger them well enough by mixing up strengths, though.
Anyway, I think we’re going to some pretty esoteric places in fireball design space, and not coming up with anything all that compelling. It leads me to believe that maybe the normal fireball isn’t going to see much in the way of substantial change.
What I am thinking, is that it’d match the hype they’re trying to drum up here if Jago got either a super endokuken (which you might spend two stocks of shadow, or full instinct, or both, on?), or an endokuken-based ultimate or no mercy. In particular, a fireball you could only throw when your opponent is in danger mode that instant kills on hit could add something interesting to the late game.