The importance of a solid launch lineup for a new piece of hardware can't be understated.
For the sake of argument, let's accept the predictions of most analysts, who say the PlayStation 4 will launch between 2013 and 2014. Considering the time gap, let's see what Sony exclusives might be ready for that time frame; the PS4 will undoubtedly need a few big hitters right out of the gate.
Gran Turismo 6
If we take Kazunori Yamauchi's reputation for being a perfectionist and the sheer amount of time involved to create a franchise entry, it's not a stretch to assume GT6 won't be ready for a few years. It'd be an especially alluring title for the PS4 launch because it's almost guaranteed to haul down high review scores and big sales numbers. This is one of the most popular franchises in history, remember.
Hardware launches are typically found around the holidays; Sony will likely want to release new Uncharted titles in that same window, and we're talking about the most critically acclaimed series of the generation. Sony well understands the importance of what has become a flagship and suddenly iconic franchise; to have a new installment ready for the new PlayStation would be epic. Naughty Dog and the PS4 would make for a lovely couple.
Guerrilla may be working on a new mystery project but they will invariably make a fourth Killzone , and it should fall into the 2013/2014 time frame. The PlayStation 3 launched with an original exclusive IP in Resistance: Fall of Man , and this generation has proven the necessity of big shooters. Plus, KZ3 was a massive technical achievement; can you imagine what Guerrilla could do with the PS4…?
Metal Gear Solid 5
Good God. Just think… These projects take time and like Yamauchi, Hideo Kojima is a perfectionist and won't be happy with anything less than a near-flawless production. Along with Gran Turismo , this is one of PlayStation's original exclusive masterpieces. To have a fifth entry available when the PS4 hits store shelves would make for an explosion of interest. Long-time Sony fans and new gamers alike would be impressed.