Another thing to consider is how Nintendo views the differences between the devices. As they themselves say in the financial report explanatory material that came out after the OLED was announced:
Source (quote is from page 12):
https://www.nintendo.co.jp/ir/pdf/2021/210805_3e.pdf
Even here, just eliminating the OLED would be the easiest way to maintain those differences, but that's assuming the new Switch will just be marketed as an OLED with better internal specs. A more Nintendo-like solution, one focused on preferences and lifestyles, would be some external add-on that comes included with (and only works on) the new device.
I can't imagine what that could be, and it would bring up the question of how much more expensive the new Switch could become because of it, but it would be a very uniquely Nintendo move.