My Worst Case scenario estimates are...
PS3 Sells like DC - 10 million
360 Sells like Xbox - 25 million
Wii Sells like N64 - 33 million
My more reasonable "pessimistic" estimates are...
PS3 Sells like GC - 25 million
360 Sells like N64 - 33 million
Wii Sells like SNES - 43 million
My lukewarm estimates are...
PS3 Sells like N64 - 33 million
360 Sells like Genesis but better - 40 million
Wii Sells like NES - 63 million
This is based on short to mid term though, things will definitely change.
Playstation 5 vs XBox Series Market Share Estimates
Regional Analysis (only MS and Sony Consoles)
Europe => XB1 : 23-24 % vs PS4 : 76-77%
N. America => XB1 : 49-52% vs PS4 : 48-51%
Global => XB1 : 32-34% vs PS4 : 66-68%