I'd say:

• Gran Turismo 6 - This will help sell the console particularly well in Europe and Japan.
• Uncharted 4 - Uncharted is now a huge, well-recognised franchise for Playstation gamers. This will surely sell it. Aldro will shit bricks. 
• Metal Gear Solid 5 - Hopefully SONY don't make the same mistake they made with the VITA not having a system seller in Japan at launch. This would be the perfect game because aswell as driving units in Japan, it appeals to western audiences and will do the same there.

I think these 3 games at launch would help the PS4 take the top spot, or at the very least make it a very worthy competitor, provided the price is right.

What do you think?

Final Fantasy VII remake, Gran Turismo 3 remake, and Uncharted 2 remake.

Well you have all 3 regions covered by:

GT 6 - Europe
FF XV - Japan
GTA something - Europe/America

Of course, I take CoD and FIFA as a given to further help sales in US and EU (mostly UK for both games)

Gran Turismo 6 if it managed to look like a definite improvement...

Uncharted is meh... didnt seem to save the Vita.
MGS... isnt as huge as it used to be.

I would say that something like an exclusive Elder Scrolls or Mass Effect could make a difference. Remakes of Oblivion, FF7 or Mass effect 1 for example.

Also, an online MMO could give the network features a good push. SWTOR, WoW, GW2, TERA, PSO2... things along those lines.

It will all depend on the hardware itself to look appealing to customers. Its gonna be dificult if all we get is theoretical more power, like the Vita and the PS3 offered.
Sony should put more focus on the features that set the system apart like the free network play and/or beeing the hardcore machine for example (if thats what they are going for) or whatever inovating feature they bring that is actually useful and not a "backrub" that server little purpose. No one cares about a check list, we want to know what it is that we get with the PS4 that we wont get with other systems. Thats how you market product. Sony needs to learn or re-learn that.

GT6, Unch4rted, Monster Hunter 5, Call Of Duty : Modern Warfare 4, Assassin's Creed 3's sequel, Little Big Plan3t

Perfect line-up, sales wise.

Ye I agree with those 3 but I would also add in god of war 4. Ps4 would be off to an absolute flyer with those 4 games.

Super Mario Galaxy 3, Zelda: Sword of Kratos and Pikmin 3.

Joke aside, I think your selection is good. Monster Hunter or Dragon Quest would be a better Japan-seller. Final Fantasy would be a worldwide seller, but that is unlikely at the launch. Maybe some good shooter.

every exclusive that has ever crossed the 2.5m unit mark.

God of War 4 - America
Gran Turismo 6 - Europe
Dragon Quest XI - Japan