IIRC, Robin Williams (who was a big Wing Commander fan, and had come to visit during the Wing Commander IV shoot) expressed an interest in doing it, but when it came time to actually make it happen they weren't able to get through his agent.
The intro scene would be safe to shoot, since all the characters die
The other scene it apparently really hurt to cut for budget was the very ending, which would have had a medal ceremony... that'd be a lot harder to make up today! (As the CGI face of Paul Walker driving off to heaven shows us...
)