segio526 :
My guess would be that the Haswell Refresh chips support DDR4 and probably fit in the Broadwell socket/boards. These may also be considered lower end chips if they stay dual and quad core since the new rumor for Broadwell is hexa and/or octa core for the i7s (not just the Es).
Nope, from all that i've heard, only haswell-E will be DDR4, refresh will be on the z97 chipset, afaik that only adds sata express.
Broadwell won't launch for desktops (thus there will be no soceted retail boards), and given the mobile focus, hexa/octa core broadwell is unlikely. DDR4 may be likely, though.
Skylake in 2015 has DDR4 for sure.