PCM was easier to sell against the field-driven MRAM that Everspin or Crocus made, since it could scale better. But now it could have a more difficult time against the new STT type MRAM. But a big difference is the MRAM resistance is becoming negligible or at least smaller compared to the transistor itself, which can be 20 K-ohm or more. Any resistance-based memory therefore cannot have a minimum resistance less than say 30 K-ohm, and equivalently, maximum current cannot exceed say 40 uA. The first condition is harder for MRAM, the second harder for PCM.
It is also interesting that Yole bracketed PCM and MRAM together to indicate a market size they think the two technologies together could reach but saying nothing about each one.
By 2016 it could be MRAM 100 percent and PCM 0% or vice versa.
Almost certainly the absolute number will br wrong and the perentages somewhere between the two extremes I've outlined.