I'm not really sure if I buy it, I think this is more of some devs maybe being in the dark/half-dark and putting things together where they don't exist or confusing the successor hardware with a mid-gen refresh.
Nvidia wasn't going to just randomly make a custom GPU for Nintendo for free, and if Nintendo paid for a redesign, I'd say there's little to no chance they wouldn't use it, they're way too cheap to spend a good chunk of money on a chip and not use it. This isn't the 90s anymore, chip designs cost a lot of money these days.
If you look at the Tegra X1 and Tegra X2, aside from the die shrink (Mariko) it's not like Nvidia offers those SoCs with like extra CUDA cores + extra ARM CPU cores ... it doesn't work like that, not just for Nintendo but for basically any vendor that uses the Tegra chips.
