Samsung's OLED displays are pentile, so I would be pretty disappointed if it's used for a portable console. For every pixel the hardware renders, only 2/3rd of a pixel is displayed. Also they are laid out in more of a chain-link-fence diamond pattern instead of a square grid, so straight lines look jagged. That's not great for text, pixel art, and classic Nintendo games. To me, they only look good at crazy-high (pseudo) pixel densities, which is a waste of rendering power and battery life. The QHD screen on my phone looks like it has a FHD screen, essentially. Which still looks good on a phone.. But you look at an older "720p" Samsung OLED screen on something like a Galaxy S3, it's pretty chunky. The jagged text is super distracting. That's probably the approximate pixel density and price/quality bracket for what Nintendo would use if they put a 7 inch1080p screen in the Switch. Maybe they could brute-force their way around some of that with a 1440p screen and a good upscaler, but I wouldn't expect Nintendo to chase numbers like that.
At least the color is nice ot these oleds, and they've gotten better at making the screens visible in sunlight and glare.