Well, it's kinda funny that no one mentioned next D700 (D800?) with FF sensor will easily beat k-5. Some people just want/need the best gear and that's why FF's are there. That's why so many people are wanting/waiting for FF Pentax just like cintelli. Newer APS-C will catch up eventually but there will be 1-3 year gap. Canon, Nikon (and later Sony) knew this logic. It's not that we ever really needed FF but it's where the money goes.

I don't think FF will die soon. Not to mention the manufacturing sensor cost goes down. Again it's all marketing. I read Sony even made their NEX system compatible with FF. If 4/3 system showed same performance with APSC, it would be so different. Just for the same reason, they are making so called premium p&s like LX5 and XZ-1 with lager sensor - just pull out little more performance ahead (which will be eventually caught up by.. iPhone6??)

I think Pentax FF really depends on the success of K-5 (and K-r). They surely want to join the pro market but again that's only if they can be profitable.