Sticking in a slightly bigger OLED screen and calling it a day is doing precisely that.
In this case, this seems more like a move to keep the expected MSRP from falling, while keeping sales high, without increasing the cost of manufacturing. I wouldn't be surprised if this new OLED model phases out the Mariko model.
I'm curious as to how this impacts the likelyhood of a Switch successor arriving next year? If the OLED model sales keep pace with current sales, I wouldn't be surprised if Nintendo wouldn't release a new Switch until late 2023.