Having a different lead singer will hurt them much more than any loss in creativity. I mean, how many bands have seen a third lead singer (not counting bands that featured multiple lead singers at the same time like Floyd, The Beatles, etc.) widely accepted by the fanbase? Probably not many. Maybe Sabbath. Any others? Not saying it can't happen, but the Spock's fanbase has already dwindled in recent years anyway, and while I think most who are still fans will give anything new they do a chance, they have a major hill to climb. Spock's has such a unique sound, and the vocals have always been a big part of that. When Neal left, NDV took over, and while it was different, his voice was already a part of the band since he was always a part of the harmonies and the occasional lead vocal (like Carie, Looking for Answers, etc.), but anyone else will be brand new and their voice will naturally be different, unless they go the Priest or Yes route and get someone who sounds a lot like Neal or NDV.