I asked Jason Attard (Senior Game Balance Designer) about whether or not we intend to bring the white crystals back. He said that we do intend to make this crystal available again in the future, but we do want it to remain very rare even when we do.
We were told that white crystal would not return for a "long, long time". So I guess that meant for like a month or two until everyone started crying? Can I have my 2.5 million credits back???
"That's a one-time opportunity during patch 1.1.5 that will likely not return for a long, long time."