That's a nice video presentation, and I like how you have cleaned up the animations in some moves and made them a little more fluid and smooth. But I was hoping that you'd make his basic moves a little more accurate to his character.
Later if you feel like editing him again, you could get some more ideas on his basics and attacks from The Death and Return of Superman, and Justice League Task Force games.
Re: CvtW Superman (using Hannibal's sprites with edits and new palettes)
It is really great that you're adding Superman into your game 'cause it seems like it will be very good. I'm not sure if you would want to edit his outfit, but in the current comics it has changed a little bit. Since you haven't really started on him yet, I thought that I would just show you a few pictures of how it looks now. It's similar, I should say (Jmorphman is right) to the one you see him in, in the Injustice game
Some of the characters we have now, we definitely wouldn't have. And I don't think the community would be as excited as it is sometimes. With way less creations, less creators, and less enthusiasm, because no other engine was as exciting as the VS engine before it came out (especially after X-Men: CotA). Then when someone did create something, it'd just be based on the original Capcom or SNK engine. Some characters wouldn't even be possible because they just wouldn't work without the mechanics of that engine (probably wouldn't have the sprites for some characters either).
So yeah, Mugen wouldn't be as popular, I don't think, because there probably wouldn't be such a variety in fighting mechanics that Capcom brought out with the vs engine, or even excitement; leading to a longer wait before newer innovations would come to the Mugen engine.