yeah because if you interested in a 1400 euro lens you could just buy the better 11000 euro lens.
i guess a ton of potential 100-400mm buyer will just buy the 200-400mm instead...
Actually, it would be the other way around. If the new 100-400L II zoom is upgraded in IQ significantly (considering it is already a good performer) you are easiliy in the zone of other primes in the focal length range...and the 200-400 zoom is not the only lens in question. Canon has kept several low priced older primes for more than a decade in this range, and while they are not sexy or new, given no new R&D or production line upgrades are needed for these as would be with a newer product, they are steady revenue generators.
People who will foot the bill for higher priced primes (may be not the 11K zoom customer, I agree) but somewhere in the midrange will pause and consider the lower priced high IQ competitor with the versatility of a zoom vs the smidge of IQ or f/stop they may garner by paying 3 or 5K more.
If the IQ and IS improve with the new 100-400L II and they will have to, at least a tad, to justify a newer version, this is not such a far fetched notion.
While I agree with the broad propositions above, there is no reason canon can't release a II version for $4K/5K just like the 70-200 variants. Why the assumption that the current lens will be phased out?
5D3, 6D, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L, 50L, 85L II, 135L, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 600RT x 4
I come here to learn something new, not to learn how bad my gear is - I know that already ;-)!