A lot of the trackless blue sky concepts had a lot of neat ideas, like the scramble through the forest in the Monsters Drive-In Concept, or characters following you in their own vehicles on the Secret Life of Pets.
But even though Universal had all these great ideas, they still couldn't crack the concept, whether that was in Pets, Monsters, Lorax, Villain-Con, or the Ministry of Magic, not to mention the countless trackless ride concepts we don't know about. Consequently, I think it'll be a while before we see a trackless concept from them.
I think a ride system where you can lock onto a track after trackless moments might be a more versatile system. It could be a system that purposely limits freedom of movements to scenes where it is absolutely needed, poses a smaller technical challenge, and saves the space these rides tend to eat up. Rise technically does this already.