This looks so completely awesome. Already in those two videos they've introduced two totally new gameplay concepts that could be used in all kinds of creative ways - the "squash" (I assume) attack, and the over-under water section. Hopefully this one getting a console release will make some heads turn, though I imagine the battle will be hard-fought as always. Regardless, I'll try my hardest to push this game on here. The first two were two of the best GBA games, easily, and I can't imagine the Cube version will fall short.
Also, the multiplayer modes in the two GBA games are completely fantastic. They're some of the only GBA multiplayer modes that I've spent a substantial amount of time with, and they're a total blast with all kinds of gameplay variations in addition to the standard race. They'll translate awesomely to a split-screen setup.