Won't happen.
N64 - No revision
GameCube - No revision
Wii - Revision years and years later
Wii U - No revision
The Switch is a home console with the ability to play on-the-go, I don't think Nintendo see it as a portable with the ability to play at home
The Wii had two revisions.
The Wii U was a flop, and as such didn't warrant any hardware revisions.
Nintendo also played about with hardware variations for both the N64 and GameCube. The projects (with the exception of the N64's expansion pack) all failed.
Meanwhile, the DS and 3DS went through umpteen hardware variations.
I don't think you can really look to history for any indication about what Nintendo has planned for the Switch TBH..