Hendo Hoverboard
It doesn't go on water. And unfortunately, it still doesn't go on regular pavement. But the Hendo Hoverboard is as close as you're going to get to BTTF 2's future without getting your face wet. Compared to the original, it has an improved power system, better traction, and better control, thanks to a skateboard-inspired design helped along by Tony Hawk. The engines are more efficient, there's a safety switch so you don't get thrown off, and the stronger engines ensure you won't hit the ground on a sharp turn. It still needs magnetic field architecture to operate, but with the tech's earthquake-proof usefulness, you might be able to skate wheelless around Hill Valley sooner than you think.