Yes, they are scanning the film elements in 4K, like a lot of the labels do, that does not necessarily mean they are planning to release a 4K UHD disc.
The 12-31 date is a placeholder (it's a Friday, so that's the giveaway). Also, they do not state anywhere in that blog post that they are releasing a 4K disc.
This post is confusing. Nowhere do they say they're releasing a 4K UHD. And when did they release a "2K Blu-ray" of The Phantom Creeps? They aren't selling it on their own site.