I'm afraid replacing VAs is a big deal in Japan. Sometimes it almost feels like it's taboo...
They did change Chuck's VA for his comeback not long ago. And I'm under the impression that Chuck's original VA was someone well-known too.
I know it might not be the same to do so for a character that was once in the main cast, but I definitely think it's possible that they will just hire a new VA if they really want to bring her back.
It's too soon to say at this point, but it is possible that we'll get the return of most, if not all, past companions during this series. So if that's really what they're going for, I doubt they'd leave May out.