Street Fighter IV producer Yoshinori Ono revealed the greatest difficulty the game's development team faces: Lag.
"Obviously lag will be a huge problem for online play", he said. "We're working on it. It's quite difficult for 3D Street Fighter at the moment."
When asked how they plan to fix that, Ono answered that "In order to prevent the lag we're thinking about trying to balance it up at [the] user interface level and input timing. We still haven't got a complete plan as yet. We're still working on it. That's all we can say at the moment."
Street Fighter players are not used to that kind of control, but several fighting games such as Tekken and King of Fighters utilize "buffered input" systems where players can input future attack commands while the current ones are being executed.