I think as someone else said some people are being pretty arrogant.
Have yet to see a single person back up their opinion of GT5 with facts and figures about how it will beat those numbers.
By saying 10m units sold with 130m consoles to sell to does not make that view stronger, it weakens it. PS3 has only a 3rd of that install base, to expect it to beat it with that much of a handicap is laughable.