No,they go for the widest audience surely after the successes of pokemon and animal crossing.
Neither of those games had released on Switch when the sequel started development and they were already very successful series before TP came out, so I don't think this is a sound argument. Nintendo doesn't need all their games to appeal to the same audiences.
As for the topic I defintely expect it to be at least a bit darker, so it could maybe happen.
- Switch - 27m
- PS5 - 15.5m
- Xbox Series - 10m