@mariatorres @Richard_Johnson I agree. Nintendo is well aware that Switch games play at higher resolution on the Steam Deck than on Switch and without users having to pay for a Switch or the games themselves (if they care nothing for copyright, anyway). Hell, Steam has native support for both joycons and the Switch Pro controller, as well as the Switch button scheme. Nintendo is not foolish enough to think people will buy their games twice. The fact that they have done so in the past has led the Steam Deck to become the preferred method of playing Nintendo DS and 3DS games, since you can connect the Deck to an external display and suddenly have the full 3DS control scheme---complete with motion controls and a secondary touch screen---but on a TV with upscaled graphics. Nintendo makes zero money through people selling used games, and used games from discontinued consoles skyrocket in price. This is why emulation terrifies Nintendo and they insist on targeting sites distirbuting their ROMs.
PlayStation and Xbox have gone the alternate route of Nintendo since they seemingly realize their hardware is not innovative enough to compete with the PC market. PlayStation and Xbox exclusives end up on Steam as well---Xbox in nearly all cases and on Day 1 if published by Microsoft.
Nintendo is, on paper, wining the console war---because they are the only console manufacturer focused exclusively on that form factor. If they do not allow customers to play Switch games on whatever their Switch successor is, their market share will eventually decline in terms of game sales. Hardware sales only keep a company afloat for so long.