If SLoP isn't happening, I'd consider Spongebob (as rumored by them too) to be far more likely than Sing at this moment. It's an iconic IP, has potential outside of a Major E-Ticket attraction and could be a good motivator to revitalize an area like Toon Lagoon.
Sing is an IP that I am hesitant on, mainly due to that its going to have to compete with Rogue One, Assassins Creed, and Passengers. I could see depending on the success ratio of the film is on it's box office; as I would say that anything is possible. I would think SLoP is far more likely though; at least for Orlando. And as for Hollywood, i would think that it's a bit too far down the road for anything to change.