i think the plot would go something like this:
That robotenza was made by Dr. Wily while he was missing to take over the world (as always) using the infected robots, roll gets sick, blah blah blah, wily has the vaccine, megaman has to help Dr. light to create a vaccine, the 8 RM have parts of the machine, you beat them, Wily appears, he steals the vaccine light made, Megaman has to get it back (wily fortress starts here), you clear the castle and defeat wily, he apologizes, wily destroys the castle, you recover the vaccine, the end.
i don't know if the alt. characters will have separate storylines, also, the maverick virus was created by dr. cain while triyng to create reploids and having a mistake in the process...
or so i heard
-EDIT-
i got inspired by sheepman and i tried to sprite him:
i think Capcom will do it 999% better