I don’t use this lens but my guess is that it will be discontinued. I believe 24-70 F4 is overpriced for marketing reasons. Canon try to make as much money as they can from a new lens but in a few years, it will probably at the same price as the 24-105 is now.
They are not priced far apart at the moment, especially when on sale, as today at Amazon. See attached screen shot below.
The 24-70 fits very well with eos 6D (better than 24-105).
Why do you say it "fits [better]"? I like having the 24-105 and a 24-70 2.8. I have no need for a 24-70 f/4.
For 5D3 or 5D4, the IQ of 24-105 may become limiting with new sensors.
Actually, with built in profiles in the 5D3 the 24-105 is quite acceptable. Can't say anything about the 5D4. It's not a 24-70 2.8 II, but I'd rather have the 24-105 on my camera than a 24-70 f/4 unless I was sure I wasn't going to need the longer focal length. It's not huge and it's useful for a wide range of applications. I often use it for street shooting. It's also a heck of a lot better from 71-105 than is any 24-70, but especially the 24-70 f/4.
As to the OP, why the paranoia? Even if Canon discontinues the lens, they will still provide service for quite awhile. If you're not going to buy something because you think it's going to be replaced soon, you'd never buy a computer, or a mobile phone, or a camera, or a car, or even a cooling system for your home. My guess is that your camera will be "replaced" sooner than that lens, unless perhaps you just bought a 70D, and even then it might still be the case. It's just a guess and YMMV of course.