I'm not saying Sakurai is lying, but, he is a troll a lot of times.
However, yes, the time does not seem clear when it comes to what they could or would add in tomorrow's presentation.
I can imagine 15 min would be Terry, the stage, eventual alternative costumes, origins, spirit, mii costumes, music, etc.
A new mode is rumoured, and would make sense with the time, even if it's up for debate.
If there is a new character I think it will be a lil surprise. Don't expect it, but some trolls likes the element of surprise.
Previously known as;
The Street Fighter 2014-2021.