512GB SD Cards are pretty cheap these days ($50) ... you wonder how long it will take for 1TB cards to get into that price range.
They would alleviate the cart issue quite a bit, even though people hate it you could have just a 32GB cartridge with enough of the game on it to get you up and playing and the rest on SD Card.
Maybe Nintendo can do two SD Card slots for the next Switch, that would help expand storage a lot too. I'd assume probably 128GB on board flash.
512GB should be fine for switch 2 since i think textures will only need to be 1080p resolution and then there will be DLSS to make it look like 4k.