GE has been quoted as having developed new technologies for the 9X blades which allow them to be thinner than previous designs; 4th generation fibers and resins, with blade-thickness similar to conventional metals.
Honestly GE's experience and success with their composite blades seems to be absolutely dominating in the current market. I'm sure RR will begin work on studies for production and such, but to completely master the processes required is unlikely for a while - and they won't be able to leverage an already mature, reliable product and production method like GE seems to have done for the 9X after the 90. GE's scale (not only in manufacturing / quantity) but SIZE is vastly different as well, the -115 and 9X are no "demonstrator"-sized fans. They also have locked-down, flight-ready engines.
I imagine we're watching the same scenario initiate all over again with their use of ceramics - bite the bullet now when you have a massive infusion of R&D cash for a huge contract like the 777X. Again, in a few years, other companies will be forced to study these materials to remain competitive (I realize many already are, but again - GE's use has resulted in essentially a certification-ready design already.)
Personally I think they have essentially locked-down the 'very large' engine/thrust portion of the market, to a certain degree - everyone seems happy with this as well.
