Masachika Kawata, the producer of Resident Evil 5 has spoken to U.K magazine GamesTM recently. I this months issue Kawata-san was asked the now very old question - Would Resident Evil 5 work on the Nintendo Wii?
He replied with the following:
Hypothetically speaking, the Resident Evil 4 engine would work perfectly for replicating the gameplay but we would never be able to recreate the graphical quality. A gun shooting game like Darkside Chronicles makes much more sense for Wii so, in short, Resident Evil 5 Wii Edition isn't likely to happen. Having said that, Cavia has surprised us with the quality of graphics in Darkside Chronicles, so it may actually be possible after all...- Masachika Kawata
Thoughts Giant Bomb?