Yes, in terms of Dolphin's performance today, I don't doubt it. There are probably many more optimisations that can be made: Dolphin's AArch64 JIT is still pretty incomplete and inefficient compared to the x86-64 JIT, for example.
My point is in theory, given enough time and effort, the Pi 4 should have more than enough power to emulate a 20-year old device. I'd argue that it's certainly not "way way too weak" as the reply above suggested.
To elaborate a bit more on the GPU peak FP32 perf:
> VideoCore VI @ 500MHz: 500 [MHz] x 2 [slice] x 4 [qpu/slice] x 4 [processor] x 2 [op/clock] = 32 Gflop/s
which is the RPi4 config.
compared to a Snapdragon 800: 147.9Gflops FP32, and that's still a very old part.
And about the Wii itself:
> With the Wii, Nintendo opted to go with an innovative control scheme, rather than to focus on processing power. It offered 12 gigaflops, which represents a 1.27x improvement over its GameCube predecessor
The margins are way too slim when counting emulation overhead.
My understanding is that the VideoCore architecture was initially designed as more of a "media codec coprocessor", and was incidentally able to grow enough matrix math throughput to be pressed into service as a GPU.
It was probably a sane technical choice for them. RPi4 is made on the same node as the Snapdragon 800 (28nm), but with a much more recent (and bigger) CPU complex, using the Cortex-A72.
My point is in theory, given enough time and effort, the Pi 4 should have more than enough power to emulate a 20-year old device. I'd argue that it's certainly not "way way too weak" as the reply above suggested.