I can see Sony approaching this on two different fronts. And given the market disparities between them it would make sense.
1. Position the PS4 directly against the Xbox in North America. Do NOT bundle in the Vita with the system as a controller option.
2. Position the PS3 directly against the WiiU in Japan where they DO bundle in the Vita with the system as a controller option.
The challenge lies in Sony being able to allocate the resources to wage war on both fronts. I don't believe they do. They should probably focus on Option #2 in the short-term and only focus on Option #1 when they have the resources to do so.
Problem with option 2 is that they'd need valid games to win the customer over. The Wii definitely has a head start and its clear Sony doesnt have any games for that atm, but still quite a lot of time to work on the PS4 plan. I dont think the PS3 + Vita connection was ever really planned as more than a gimmick after seeing that Nintendo did it.