Anymore bold prédiction ?

This U4 will sell at least 9M at worse

No way will it sell 10 million.
Only open world adventures, FPSs and sports games can sell 10 million+ nowadays.
And occasionally Mario or Pokemon.

The best Uncharted has done is about 7 million. I think this will probably end up around the same.

The Last Of Us sold over 11 million. Uncharted 4 can do that. Naughty Dog has a huge fanbase new and old, Uncharted is a popular franchise and Uncharted 4 is releasing with huge hype.

That and we don't know how well the best Uncharted game did. All we know that the average sales of the trilogy was 7 million by last year, may be higher now. If VGC's ratio for sales of Uncharted 1-3 is correct both 2 and 3 should be above 8 million.

Math, how does it work...

I believe Gears of War 4 will sell 5 million lifetime, while Uncharted 4 10 million.

Pretty agree with this prediction, yes.

lol wut?

Also, Uncahrted 3 and 2 sold well over 7 million.

PS4's sold 85% faster than PS3 has, so sales of Uncharted 4 will likely reflect that. Uncharted 1-3 sold on average about 6-7 million units, just going by those 2 factors Uncharted 4 should sell at least 11 million units, but then there's the fact that Naughty Dog have way more prestige than they've ever had before, their public image is at an all time high.

Uncharted 4 has gotten ridiculously high praise, which is very important for sales this generation.

Gears 4 on the other hand is no longer being developed by Epic, but rather an unknown studio, with no history making games as a whole studio. Gears 4 isn't getting anywhere near the kind of buzz that Uncharted 4 is and this is the series 5th mainline release, so it has more fatigue.
Gears hasn't shown anywhere near the same level of update to gameplay features as Uncharted 4 has and the game hasn't been marketed much at all either.

Xbox One is selling about half the numbers of PS4, but even Halo 5 hasn't blown up in software sales, struggling to hit 4 million units so far.
Gears was always the slower seller on Xbox, so I doubt it will manage 3 million units lifetime.
No I don't think Gears 4 will get anywhere close to sell half of Uncharted 4's numbers, best case scenario it may sell a third, most likely around a quarter.

my prediction is life time. and to be honest, i didnt read the post you quoted, so if the comment was by the end of the year, i didnt pay attention to that. 

Uncharted would sell better then Gears if they where both on the same console, uncharted is launched on a console with roughly twice as many sold units, this seems like a sure fire bet