In the latest Nintendo Direct, they announced that Mario Kart 8 Deluxe will be having more tracks via booster pass consisting of six waves. Each one having two cups having the typical four tracks per cup from March 18th this year, to the end of 2023. So far, we only know that each cup will consist of only retro tracks from Super Mario Kart to Mario Kart Tour(which is ironic since that game came before 8 Deluxe). The tracks we have so far are Tour Paris Promenade, 3DS Toad Circuit, N64 Choco Mountain, Wii Coconut Mall, Tour Tokyo Blur, DS Shroom Ridge, GBA Sky Garden, and Tour Ninja Hideaway. These are the tracks I think will come to the game's booster packs in no particular order. A little disclaimer: I never played Mario Kart Tour before, so I don't know how any of the tracks are designed as well as what obstacles are laid out. So to replace tracks from that game, I used ones from the arcade game instead, which I hope has a chance of coming to the game as well.

Super Mario Kart
Mario Circuit 2, Mario Circuit 4, Vanilla Lake 1, Donut Plains 2, Bowser's Castle 2, Koopa Beach 1

Mario Kart 64
Mario Raceway, Wario Stadium, Kalamari Desert, Frappe Snowland, DK's Jungle Parkway

Mario Kart Super Circuit
Riverside Park, Cheep Cheep Island, Rainbow Road, Boo Lake, Snow Land

Mario Kart Double Dash!!
Wario Colosseum, Mushroom City, DK Mountain

Mario Kart Arcade GP 1 and 2
Pac-Labyrinth, Diamond City, Mario Beach, Bananan Ruins, Waluigi Stadium, Castle Wall, Rainbow Coaster

Mario Kart DS
Mario Circuit, Bowser's Castle, Airship Fortress, Waluigi Pinball

Mario Kart Wii
Toad's Factory, Dry Dry Ruins, Moonview Highway, Maple Treeway

Mario Kart 7
Rock Rock Mountain, Mario Circuit Rosalina's Ice World, Maka Wuhu, Wuhu Loop, Wario Shipyard