My logic clashes with your prediction of the future, not with reality or facts. If you look at Canon's lens lineup, there is lots and lots of duplication. How many versions of the 70-200? And of the 70-300? There are four 50's. It's not a stretch to conceive that maybe the 24-105 is not being replaced by this 24-70.
Yep, why stop a bestseller?
How about this marketing scenario: Sell the 24-70 F/4 with a camera kit. People buy it and later if they want some extra range in one zoom, they have to buy the 24-105 also. Double money
5Dmk3, 5Dmk2, Sony NEX-6 | SY14mm f/2.8, Ʃ20mm f/1.8, 35mm f/2, Ʃ35mm f/1.4A, 50mm f/1.8 I, Ʃ50mm f/1.4 EX, 100mm f/2.8L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 70-300L, 100-400L | E-mount: 16-50 OSS, Ʃ30mm f/2.8 EX DN, 55-210 OSS | 2x FT-QL, AE-1 Program, some FD(n) & FL primes