I never said that piracy is the ONLY factor for a consoles death, in case of the Wii U, that already has more than enough problems, it really could be the final nail in the coffin.
1-3 % ? ... in these days?! This is what i say to your 1-3%: Conversely, there's no substantiated evidence that only 1-3% of the users are pirates.
1-3 % ... from what RELIABLE source are these values? If you type a consoles name into google.com, the first or second suggestions from google are the console name + "hack", "custom firmware", "homebrew" or "emulator".
Depending from the system i would say: 20-30%.