In the future, in the months after Legacy of Romulus launches, warp cores will be obtainable by other methods as well, with some special Romulan duty officer assignments to build singularity cores, as well as a suite of cores being added to a Fleet store. Obtaining a desirable warp core should be no more difficult than obtaining a desirable deflector array or impulse engine.
Glad this was finally confirmed, but it's a shame it won't be for launch!
I'm really excited about this, great new mechanic IMO. Thanks for the news Brandon!