Live on stage just now at Sony Paris Games show, Capcom has announced that in addition to the 16 characters on launch for Street Fighter 5, six additional characters will be released within the first year. It was not mentioned whether or not these will be simultaneous or indivdually, but the final count will be 22 fighters year 1.

No additional info was released, but the launch date of February 16th, 2016 was in fact confirmed. 

https://www.youtube.com/watch?v=8V-lQ1WVvok