Ok, so after watching the "Drill Mount Spoiler" a few times, I came to realize that the glowing particles coming from the blocks as they are mined are most likely energy that the mount uses, to keep it going. That way you cannot use it to just fly around all over the place, you'll actually have to use it to mine.
OTHER MOUNT SPECULATION
-"Car" Mount. (A mount that is able to traverse the land and you can go over enemies/ blocks. It would be a easy transportation tool)
-"Submarine" Mount. (Able to explore underwater with unlimited oxygen and protection. (I predict that there would be many new underwater minibiomes that you will be required to have this mount in-order to explore) I think that the biome would be a sunken ship/underwater temple)
Let me know what you guys think of my predictions. Thanks!!
- vimio (Brent)