One thing to note is that while Hynix's have numerous patents related to phase change memory they have only one ReRAM/memristor patent (for an application in RFID). Thus all else being equal there is more economic incentive for Hynix to develop phase change memory. Below is a link to comparative US patent data for companies invested in memory resistors vs. phase change memory.
The way SK Hynix approaches these memories, by sharing risk with big names like Toshiba for STT-MRAM, HP for memristor and IBM for phase change memory, indicates they are not really into using these in the near future. So it's funny to watch the big-name partner get all excited and make optimistic projections.