I DONT think everyone needs an air dash, but I do think that if a character doesn’t get one, there should be a conscious effort to give that character other aerial mobility options. Every character should not be Magneto. For example, if you took MvC2 Psylocke, and rebalanced her hitboxes and frame numbers vs. trijumps you could balance that matchup with out giving her a tri-jump and a Rom.
Short hops sounds pretty good to me, because it would allow everybody to get an instant overhead game right off the bat. If you don;t get an air dash, you should be looking at at least a double jump, float style move, or something similar.
On another note, Capcom can’t make the mistake of nerfing the returning God Tier characters, what they need to do is give everyone the tools to fight them. Basically Storm/Sent/Mag/Cable should all play the same, or close to the same. If the overall game is going to be slightly slower-paced or w/e, then at least keep it relative, but everyone knows that Marvel is about speed and reaction time, and combos where every point of damage is earned through execution. Marvel has always been about shattering the boundaries of execution barriers, I wholeheartedly feel that tampering with the high level execution requirements would be a major affront to the series.
Please understand the reason why the God Tier in vanilla Marvel have allowed the game to thrive for a decade at high level play-- their mobility and combo system is so open, that it’s allowed for a progression of constantly re-upping one another. As one character evolves, the rest are forced to reach into their bag of tricks to find a counter. Basically give everyone more moves and options than we know what to do with, players can take it from there.
Don’t change the core of the blocking system, aside from twitch guard (it might be beneficial to at least attempt a proximity based system for this), its really solid.