I'm not sure if this is an unpopular opinion or not, but i would rather they stick with priorizing courses that haven't been remade ever, i also think tracks that have only been only remade in tour and/or super circuit are also fair game. I'd much rather if they left already remade retro courses for DLC.
Here are my predictions:
Shell Cup
DS Figure 8-Circuit (Never remade, i think it would serve as a nice introductory retro track even if it's kinda boring, specially if the 24 racers rumour is true, peraphs it could have some antigravity stuff)
3DS Daisy Hills (Only remade in Tour, a simple course that could be easily be added into the shell cup, not much else to add)
SNES Koopa Beach 1 (Only remade in SC, Yeah this is a very simple track, but i think it works well as a filler shell cup track, the water could also make the track more interesting)
Wii U Thwomp Ruins (Never remade, i think this is one of the most iconic tracks ofMK8, it' such a modern classic to me, it feels like the perfect course to end the shell cup with)
Banana Cup
Wii Toad's Factory (Never remade, a fan-favourite that could honestly add very fun stuff with anti-grav, not much else to add)
3DS Shy Guy Baazar (Only remade in Tour, A pretty underrated track and i think it could look really nice with a HD glow up)
Wii U Sunshine Airport (Never remade, probably the most popular new track from MK8, not much else to add.)
N64 Wario Stadium (Never remade, the only n64 track left to remade, i think it would work well with 24 players)
Leaf Cup
Wii Mario Circuit (Never remade, Yeah, peraphs a bit unusual for Leaf Cup, but eh Kalamari Desert was in the Leaf Cup in MK7....so why not)
Wii U Electrodome (Never remade, another MK8 fanfavourite, not much else to add)
GCN Mushroom City (Never remade, a fan favourite from CGN that has never been remade, i think it would be chaotic for 24 players, but in a fun way)
GBA Broken Pier (Never remade, This could fit the bill for the "scary track")
Lightning Cup
Tour Piranha Plant Pipeline (Never remade, i think this track is very unlikely to get in compared to the others, but it's the only one that hasn't been remade from Tour)
Wii U Super Bell Subway (Never remade, yes this is a dlc track, but i think it's pretty popular so why not?, also imagine the chaos with 24 players!)
DS Bowser's Castle (Never remade, i think this track is very underrated and it would make a fun track with 24 players)
GBA Rainbow Road (Never remade, not much too add, it's the next one in line)
Here are my predictions:
Shell Cup
DS Figure 8-Circuit (Never remade, i think it would serve as a nice introductory retro track even if it's kinda boring, specially if the 24 racers rumour is true, peraphs it could have some antigravity stuff)
3DS Daisy Hills (Only remade in Tour, a simple course that could be easily be added into the shell cup, not much else to add)
SNES Koopa Beach 1 (Only remade in SC, Yeah this is a very simple track, but i think it works well as a filler shell cup track, the water could also make the track more interesting)
Wii U Thwomp Ruins (Never remade, i think this is one of the most iconic tracks ofMK8, it' such a modern classic to me, it feels like the perfect course to end the shell cup with)
Banana Cup
Wii Toad's Factory (Never remade, a fan-favourite that could honestly add very fun stuff with anti-grav, not much else to add)
3DS Shy Guy Baazar (Only remade in Tour, A pretty underrated track and i think it could look really nice with a HD glow up)
Wii U Sunshine Airport (Never remade, probably the most popular new track from MK8, not much else to add.)
N64 Wario Stadium (Never remade, the only n64 track left to remade, i think it would work well with 24 players)
Leaf Cup
Wii Mario Circuit (Never remade, Yeah, peraphs a bit unusual for Leaf Cup, but eh Kalamari Desert was in the Leaf Cup in MK7....so why not)
Wii U Electrodome (Never remade, another MK8 fanfavourite, not much else to add)
GCN Mushroom City (Never remade, a fan favourite from CGN that has never been remade, i think it would be chaotic for 24 players, but in a fun way)
GBA Broken Pier (Never remade, This could fit the bill for the "scary track")
Lightning Cup
Tour Piranha Plant Pipeline (Never remade, i think this track is very unlikely to get in compared to the others, but it's the only one that hasn't been remade from Tour)
Wii U Super Bell Subway (Never remade, yes this is a dlc track, but i think it's pretty popular so why not?, also imagine the chaos with 24 players!)
DS Bowser's Castle (Never remade, i think this track is very underrated and it would make a fun track with 24 players)
GBA Rainbow Road (Never remade, not much too add, it's the next one in line)