WDW1974 mentioned a few months ago that WDW would eventually get California's upgrades sometime fairly soon. I don't know if this is the one that will do it but California's apparently closed from March 20th to May 10th I believe when it got its upgrades, somewhat more than a month's worth. Though some of that time may have been to construct new scenery and figure props as well as tweaking paint and lighting, things that may not require as much time the second time doing it (they may have already duplicated the extra props during DCA's enhancements in preparation for MK's enhancements). So MK's may not require as much time.
There were rumors that DCA's would be getting even further enhancements in another refurb down the line to fix the ending scenes. I don't know if this is true, but i'm guessing they're not going to address this in MK's refurb. This isn't much time at all. We're lucky if month long refurbs even address simple maintenance issues in this day and age.
Though at least as of early October MK's version looked like it was still in good condition maintenance wise, didn't really notice anything broken. Besides the air conditioning sucking badly, though that's just TDO trying to save money on the energy bill as has been discussed. So I guess these enhancements are plausible given that I didn't actually see anything really needing to be fixed by a month long rehab (unless it's something mechanical we can't see with the naked eye).