I think next year will reveal if its leaving or not.
If we get this well rumored new family area linking the farm, storybook land and adventure land up, and Sonic gets a complete re-theme (eg new sponsor, re-paint, etc, etc), then I don't think it will be leaving the park anytime soon. However if it is left as it is, then its days are probably numbered, ready to be replaced by another new ride in the new family area in the future.
Maybe if it does get re-themed next year we could see a much better theme, queue, etc, etc and people could like it?