Further thoughts: I think if Vocaloid ceases to recieve updates or moves its focus to AI, OpenUtau will gradually become the defacto choice for concatenative synthesis. OpenUTAU is open source, so it will continue to receive updates, and it has customisation features, so it will continue to get releases. It has already surpassed Vocaloid in terms of options, eventually it may surpass it in audio quality and usability as well. With it, the traditional methods of vocal synthesis have a bright future too.