Full-size RPi isn't Arduino's competition, surely (except for the newest Uno Q, which is a novel take on a Pi-type SBC).

There are meaningful disadvantages to replacing an Arduino with even the Pi Zero.

Yeah, makers will move to Raspberry Pi products for the ecosystem and documentation, but it will be to the RP2040/2350 products.

But also the ESP32 series, particularly Adafruit's kit.