During the recent Nintendo Investor briefing, it was announced that Mario Kart Tour, the mobile Mario Kart game, would no longer release by the end of March, but instead would release in Summer 2019, or Winter for us down under.

The reason we were given for the delay as "enhance the quality and expand the service contents, such as in-game events." So either they were not happy with the quality, which given the recent Metroid Prime 4 reboot, is possible, or they wanted to add more events like other mobile games.

In any event, we now have to wait to Winter to begin driving our little karts on mobile devices, if you want to play Mario Kart mobile today, you can always pick up Mario Kart 8 Deluxe on Switch.