I hope he hasn't been replaced.
Viola, Zwei, pyrrha and pat should all return as I really like viola and zwei's concept.Also, it looks like Daishi has been replaced.
I'm of mixed opinion of Daishi- he did good in improving the gameplay standards of the series and understood the value of competitive play, but the new chars added in SC5 and some of the new mechanics didn't fit the Soul series at all and felt shoehorned in from 2d fighters.
Hopefully SC6 (which I think will happen) can take the good from SC5 (competent gameplay) , and not the bad (missing chars, dump Viola/Zwei/Pyrrha/Patroklos- they're all lame, just guard)
As for Link, I'm worried more about if Sophitia/Sueng Mina will be in- if it's a port of the arcade they might not. No Mina no buy for me.