Sometimes they don't have a choice. Adding or modifying certain features of the chip(like the integrated memory controller) can change the pin arrangement leading to a new socket, and keeping the same socket for a while doesn't always ensure compatibility anyway. Back in the Athlon XP days Socket A stuck around for years, and not every Socket A board could support any socket A chip.
Whether or not that's going to happen here... I dunno. There has been talk of Kaveri supporting "fully shared" memory between the CPU and the integrated GPU, but there hasn't been many details about exactly how that's going to be implemented in hardware.
Since nobody can see the future, I think the best you're going to get is a definite maybe. 
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Do not meddle in the affairs of archers, for they are subtle and quick to anger.
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Troll Hunter
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