I love the buggy idea, and how much mobility they provide in game. While I'm sure that there's work being done on new mounts, I think that incorporating flying mounts would be the coolest addition, compared to any other ground bug.

I get that flight might make for a lot of issues and borders that would need to be placed, but even if the bug could only fly a small distance above the grass, it would be amazing. 

My idea was to utilize the caterpillars as a way to obtain a tamed butterfly, maybe by capturing it in some way, or simply finding a cocoon which can be picked up and placed in a hatchery. If the player was able to fly on a butterfly, I think that ziplines could be left out of the game entirely, and it would be such a beautiful experience too, fluttering over the grass. I think it would be reasonable to give a max flight height, which would avoid issues with players flying too high and getting to areas where they shouldn't be, for example, the top of the picnic table, if you wanted to avoid that. 

Flying buggies might in a way defeat the purpose of exploring the park properly. This is the first thing I thought of too when they first mentioned they were adding buggies. This is why they want to introduce ziplines late so folks will use the land buggies and travel around and discovers caves, holes, secrets, perform intricate parkour to climb bins and stuff. Flying buggies makes sense but I think they'll need to limit its flying to kinda like a gliding thing by giving it a very short stamina bar or something so we don't just dart across the map.