Looks like the next batch of characters coming to Super Street Fighter 4 are from the Street Fighter Alpha universe! Cody, Guy and Adon are shown in these Famitsu magazine scans rounding out the confirmed new characters to six total.
Many interviews from CAPCOM hint that perhaps eight may be the final number of new characters to show up in the next revision of the game, but we will just have to wait and see. Sound like they are on a tight development schedule so I am sure they are trying to fit in as many characters as possible while still keeping the gameplay balanced.
Looks like Ibuki from Street Fighter 3 could be making an appearance as well. Keits from SRK pointed out that if you look at the upper right of the scan with Guy, you will see he is "parrying" a kunai (blade that Ibuki chucks out).
This isnt confirmed of course, could be anything -- a weapon that Cody can use perhaps?