I don't think Intel really cares about breaking upgradability--and I seriously doubt they would do anything to help or hurt it. The number of people that actually replace CPUs (us, the enthusiasts) is very very small when compared with the number of people that have computers with Intel CPUs.
That said, they most certainly try to use the same socket over again if they can--just look at how long socket 775 lasted. Changing a socket means retooling production lines, getting new products in the channel, and a whole lot of other NRE associated with the changeover. The fact that the new socket has 5 less pins is probably incidental; I'm sure there's significant changes to something that necessitates the change.
I heard Intel is gonna stop selling Intel brands motherboards.
They are. The market is low profit-margin and highly competitive for Intel, a company which makes far better cpus than motherboards.