They just showed off the select screen for the demo that's gonna be at EVO, and I've noticed a pattern in the UI:
>odd number of columns (3)
>even number of rows (2)
>enough space for at least another column on each side (5 total)
>plenty of space for 3 more rows above and below (8 total)
>8 x 5 = 40

There might be a base roster of 40 characters