It's always the hurdle for new IPs: "Nobody's ever heard of it; how will it sell?"
Historically, the overwhelming majority of new IPs have no hope of competing against new installments in established franchises (sales-wise).
Heavy Rain was an amazing success for PlayStation 3 but that's a definite anomaly in the world of new IPs. There's a reason why so many long-time PlayStation fans want new entries in the God of War and Gran Turismo franchises, and there's no doubt that both titles will sell exceedingly well. It also stands to reason that both would outsell any new IP PlayStation 4 can produce, including the likes of the upcoming Bloodborne and The Order: 1886 .
However, all new franchises must start out as new IPs at some point, correct? There were plenty of skeptics just before Uncharted: Drake's Fortune launched back in 2007, and now it's arguably the flagship series for the PlayStation brand. Everything has to start somewhere. At the same time, recognized names almost always fare better in the market; that's just simple economics. Therefore, is it better for Sony to keep the ball rolling with highly revered titles, or should they focus more on new IPs for the PS4?
In other words, are you more interested in projects like the one Quantic Dream is currently working on, or are you pining for those new entries in franchises that have already confirmed their awesomeness?