That's definitely a great idea, though if there's anything I don't love about Sea World (and there's not much I don't love about Sea World) it's how incredibly structured your day has to be and this seems like this has the potential to add to that.
When we were there the other day there was a lot of planning involved to figure out how to fit in Dine with Shamu, One Ocean, Clyde & Seamore and Dolphin Days and eventually we just decided to skip the last 2. Since Sea World is such a show heavy park you really have to plan everything out at the beginning the day to make it all fit since you have to plan everything around the daily show schedule. This is further compounded by the fact that the 3 best shows are outside and thunderstorms are a daily occurrence this time of year so you need to have contingency plans also.
I love the idea in theory but I'm interested to see how it's plays out. I could see this being anything from incredibly annoying to incredibly awesome depending on how it's implemented. If you go on your phone or the kiosk and reserve Kraken and it spits out a random "next available" return time then that's really annoying if it happens to be in the middle of a show you want to see. If you can choose from a list of available times and figure out how to work it in between shows then that's awesome.
I love the idea in theory and I'm optimistic but I'm really curious as to how they're planning to do this because that's going to have a big impact on how it's received. Hopefully it's more like FastPass+ and less like Tapu Tapu.