A Disney Spokesperson has confirmed to the local Southern California Media that the popular World of Color show will remain dark into 2019 without a firm return date:

Quote Originally Posted by Orange County Register

Disneys World of Color show wont be back until next year
Why the show is still closed is a mystery

By Marla Jo Fisher
Orange County Register
December 18, 2018

Disney California Adventure said Tuesday that its popular World of Color show will remain closed until next year, squelching speculation by fans that it might reopen in time for the holidays. Its been closed since April, after going down under mysterious circumstances.

We know our guests love World of Color and we have been working diligently to bring this experience back as soon as we can, resort spokeswoman Liz Jaeger said Tuesday. We are hopeful the show will return in the next several months.

... [the show] has been closed since April after an unexpected incident that occurred during routine maintenance. Accounts differ over exactly what caused the malfunction and Disney has not elaborated publicly but it was significant enough to shut down the entire show for many months.

... Disney officials said Tuesday that World of Color is a one-of-a-kind show with extremely complicated systems, including a one-of-kind fountain and that everything has to work together. During regularly scheduled maintenance in April, components that run the show that were supposed to be submerged in the lagoon were damaged and could not be properly submerged, requiring extensive repairs.