Air Ride’s big differentiator was it’s City Trial mode, where instead of racing you drove around a city collecting upgrades and after a certain period of time only then do you race (or fight or do a minigame). the new Mario Kart’s free roam mode has some overlap with that conceptually but maybe it was a late enough addition and Air Riders was too far along to scrap or something, or maybe City Trial isn’t the focus of the new game and they’re trading places. it’ll be interesting to see!