Destiny and Titanfall are imo the best candidate to grow and turn into heavy sellers. Both have a story and worlds that need to be expanded. Both are amazing gameplay wise. I think Ryse also has potential as a franchise.

Infamous has potential, titanfall I know many say is overhyped but I don't know they could build an awesome story come on you have alien dinosaurs!!!, Star Fox this is the one that has a extreme potential Gameplay could be 32 vs 32 in space/air, on foot with landmasters in exotic planets, story can be a good one and needs to be open world you can fly to different planets and be on foot like in No Man's Sky.

Uncharted, God Of War, BioShock, Gran Turismo, Syphon Filter and LittleBigPlanet have a lot of potential to grow.

TLoU certainly has huge potential to be a Super big franchise.
And Dragon's Dogma has the potential to be a big franchise as well as a fantastic one.
DRAGONS DOGMA!!!!!!

This will probably have people scratch heads, but I still think Killzone has the potential to grow, IF they give the game to a developer who can make a decent story. The universe is interesting, the tiny snippets of story elude to some interesting stuff, but to date its been a restrained to a fairly dumb FPS good humans versus bad aliens story arc. There are some cool angles they could go down, if they move away from the COD clone route.

Destiny has huge potential to grow, mainly because the first instalment provides so little of the original vision of the game. Introduce actual RPG, social elements and story structure and the next iteration of Destiny will be massive.

As has already been said, Starfox.
But for God's sake keep him in his vehicles, every time he leaves them disaster ensues.

And Starfox SNES > Starfox 64 :p

Regarding Metroid, I really feel like they could expand upon the series in a lot of cool ways.
Retro (Or was it Nintendo in general?) previously said that they'd like to expand the Metroid universe, whether that means another protagonist dealing with other Metroid in the universe (if they exist), or Samus exploring something new, both sound like cool concepts!
Hopefully that quote comes into fruition though...

Uncharted
the last of us
littlebigplanet

Haters gonna hate:
PlayStation All-Stars Battle Royale :P

It would need to be smash bros style gameplay but I 100% agree with this one.

And seriously people, god of war, uncharted, gran turismo??? I feel like you have to be taking the piss on these ones....