ntel's bright idea about transitioning between DDR3 and DDR4 for mainstream client platforms is not hugely different from how its P35 Express chipset dealt with the issue. It plans to come up with a new memory module form-factor, called UniDIMM. It's a DIMM that can hold both DDR3-class and DDR4-class DRAM chips, designed for Intel's upcoming Core "Skylake" processors.
"Skylake" will feature an IMC that supports both DDR3 and DDR4. With UniDIMM at their disposal, system manufacturers can source UniDIMM modules with DDR3 DRAM chips (which will be cheap, until DDR3 inventories begin drying up), and offer upgrade potential to UniDIMMs with DDR4 chips (which will get progressively cheaper).