From the NI Massive X Webpage:
https://www.native-instruments.com/en/p ... massive-x/Back in September we announced that MASSIVE X would arrive in February. Unfortunately, when building such a complex instrument, things can take longer than expected, so we’ve taken the difficult decision to delay the release until June.
When MASSIVE X arrives, we’re sure you’ll agree it’s been worth the wait. In the meantime, we’ll be releasing more details over the coming weeks, plus updates and inside info from the development team.
MASSIVE X will be available in June 2019. If you already own KOMPLETE 12, you’ll get MASSIVE X as a free download via Native Access. MASSIVE X is an addition to the MASSIVE family, and will exist side by side with the original instrument.
There's some more screenshots and info on the webpage.
Timing-wise, this might coincide nicely with the annual summer half price Komplete sale.