UPDATE: I appreciate the inputs and suggestions made by many, although I'm still not happy with the lack of communication up front or afterwards from Apple. Given that I'm apparently not important enough to get a responsible alert or answer from the company I paid for the iMac, and given that Apple seems to have updated everything else EXCEPT the iMac this year, I'm not exactly gung ho on buying a new computer from them. I still like the products, but not silent arrogance or false hype in Apple product webcasts. I don't think I'm alone.
HOWEVER: On the subject of Boot Camp, I gave up waiting and decided to remove Boot Camp, upgrade to Mojave, and install VMWare Fusion 11.x. After some newbie installation foibles, it does work on the late 2012 iMac/3TB combination. If you opt to do this, there is a frustrating issue that took me hours to find a solution to. During the installation and creation of your first virtual machine, you may get a vague error that tells you absolutely nothing about why it's failing to create a VM. I found the solution, not on VMWare's knowledge base, but on a community forum much like this one (but not.) Open the system preferences, then security and privacy, then the privacy tab. LEAVE it open when you create your VM and notice the insidious little security alert that shows up nowhere else and has no dialog box to reveal its presence. Some of you aces might know enough to do this in advance, and that shows you're more knowledgeable than me! Just always allow the darned thing to continue in the privacy tab and you'll be fine.
At least this will keep me going with Windows 10 until Apple decides to convince me I should buy another iMac.
