Burning Typhoon on 01 April 2015
Street fighter V will be here in 2016 at the absolute soonest. I can't really say that Ultra Street Fighter IV would even be much help, in terms of prepping you for SFV.
SFII & SFIII were vastly different from each other, adding dashes, EX attacks, universal overheads, and parries. As well as SFIII & SFIV. So, really, it doesn't matter which Street Fighter game you play. SFV will be different from all of them, while keeping only basic fundamentals.
