They can't call it 'Super' because it will lead the people who were already on the fence to postpone their purchase and wait for the "complete" 'Ultra' package. They need to reinforce the idea that this is an on-going service and entice players back through other means. Plus, backtracking on what they've said the early on about not releasing "
Super Street Fighter V" will make the move sound desperate.
They can call it Street Fighter V: Season 1 like Killer Instinct does and package DLC characters with the base game at a discounted price for $39.99 USD or less.
Eventually (towards the one year mark), I want to see the base game or cut down version of the base game with just a handful of characters go free to eliminate any reason for people not to try the game out. By then there should be a story mode etc.
Whatever they do, I think slapping the word "Super" onto the next disc based release would be a mistake that will be sending the wrong message to onlookers.