Also, the ten year life cycle thing doesn't refer to them not releasing new hardware within ten years. Both the PS1, and PS2 had ten year life cycles. The PS2 launched 7 years into the PS1's life, and the PS3 six years into the PS2's life. All it means is that Sony pledges support for ten years. It's a promise that once next gen comes around Sony won't just drop support for the PS3 like Nintendo dropped the GameCube, and Microsoft the Xbox at the first second possible.
14 million units shipped. That figure includes 4 games. Gran Turismo 5 and Gran Turismo 5 Prologue combined have shipped just under 13 millionand counting.
The other series you mentioned are the second tier pack. Resistance is basically a dead IP once Burning Skies on Vita ships next month. Insomniac is dropping the series, and it hasn't been a good seller since the first one. Killzone exists because the Dutch government heavily subsidizes the studio who makes it. As for Sucker Punch, obviously the sales for the inFamous series are well enough for Sony to want to purchase them.
An option like going third party isn't really applicable to SCE since they're so much bigger than SEGA. Sony would have to shut down a tonne more studios simply because there would be less platforms to support (No Vita, and no PlayStation Suite).
They're not going anywhere. There will be new PlayStation hardware. Heck, Polyphony Digital - who is Sony's biggest studio in terms of success, developed the assets for Gran Turismo 5 in a higher resolution than the PS3 can handle simply because it'll make for an easy transition next generation.