Why worry? If the rumor is true and a small publisher can afford to put their game on a 64 GB game card, then that would mean that every third party publisher can afford it. This would stand in stark contrast to the 32 GB game cards for Switch 1 which were very rarely used.

Seems like Capcom, Square-Enix and some others cant justify using a 64GB one, so I dont know. I swear if Elden Ring is a game-key card I will be very disappointed.

Capcom couldn't even put the full Mega Man Collection on Switch 1 on a game card, so it required a partial download despite its overall small file size that would have made it fit on an 8 GB game card comfortably. There were plenty of other examples that had nothing to do with the storage medium for physical games, hence why nobody should be surprised that this malpractice will continue on Switch 2. So file sizes and production costs of game cards really do not matter much for Switch 2 games; it's about whether or not any given publisher has a sense for basic decency and that is the part that should worry you (and me).

From what I heard a 64GB cart costs 16 dollars for publishers. Maybe cheaper when you buy them in the millions, but its expensive. Add the fact that Nintendo takes 30% and it adds up. I just think they should have more options.

The $16 must include the royalty fee that is paid to Nintendo already, because otherwise there would hardly be anything left for the publisher. Nintendo's cut is 30% for digital games, but for physical games it's lower at around 20%. That is because for digital games, Nintendo is both platform holder and retailer whereas for physical they are not.

For a $60 game, this is what a third party publisher would have to give up to Nintendo and retailers:

1. Physical: $16 to Nintendo (if rumor is true) + ~$10 retailer cut = ~$26
2. Digital: 30% to Nintendo = $18

Digital is more profitable for publishers, hence the push towards digital games.

If for physical it were $16 for the card, 30% to Nintendo ($18) and ~$10 retailer cut, you'd end up with $44, leaving only $16 for a publisher. At that point we likely would have no physical games anymore.

Well thats why the games now cost 70$ and probably 80$ soon if Mario Kart World does well.

No, that's not the reason. Increasing game development costs and times are the reason for higher prices.

20 years ago third party publishers had to surrender ~$25 on $60 physical games too, regardless of publishing on Nintendo, PS or Xbox.

It can be both reasons. The new Rune Factory game is 60 on Switch, but 70 on Switch 2. Cross gen releases are usually the same price on both the new and older hardware. But in this case I think the extra 10 for the Switch 2 version is because of the cost of the 64GB cart. 

Marvelous is selling a $10 upgrade pack on the Switch 2 eShop for owners of the Switch 1 version, so that's $60+$10. The same as the $70 Switch 2 version which includes the upgrade pack out of the box.

Well thats an optional upgrade and has nothing to do with the physical releases. The game is 60 on the Switch and 70 on the Switch 2 out of the box. Its just a simple upgrade and added mouse controls, theres no extra content in the Switch 2 game.

Also the game is 60 on PC. A version that will probably be better than the Switch 2 version. So the only thing I can think of is that the 64GB cart is the reason why its 70 on the Switch 2.