In this thread I have read several replies that want to communicate that it it is unwise for Canon to make this new 70-300 non-L lens .... well, useable.
In an ealier thread "A New Full Frame Zoom Coming in 2016 [CR2]" I wrote about my experiences with owners of the 'old' 70-300 non-L lens because I was then looking for a Canon lens with a bit more reach than my present 55-250 STM but in particular a bit faster AF than that lens. I wrote:
" .... I have spoken several people in the last year with the Canon 70-300 non-L, and both its AF-speed and IQ is not to modern standards at all. Probably Canon's innovations with STM are partly to blame for that. And innitial reviews of the nano-USM seem to be even a step better for de AF-speed. Of course, IQ is a per-lens matter, based on how Canon choses to market the lens.
But there is another aspect of the present 70-300 non-L I would like to bring up. Two of the people I spoke bought the 70-300 non-L as part of a package with a body or another Canon-lens. Both were thinking that with Canon they could not be mistaken, even although it is not that cheap (and almost twice the price of the 55-250 STM). And Canon's own words speak about good IQ and fast AF. For them it was a great disappointment that the Canon 70-300 non-L could not focus on playing children (not eratically running around, just slowly moving as any kid does), pets, etc.. These 'normal' customers are disappointed greatly: not in this lens, but in Canon as a brand!
So perhaps Canon manages to earn a lot on sales of an old design that (new) customers keep buying because it routinely gets packaged with other Canon products (e.g. around the holidays), but apparently the management of Canon does not realise that Canon is eating from it's own good name here. After this experience, both of these customers (owners of a Canon DSLR-body) will not automatically chose a Canon-lens next time, they told me!
The third was a guy I met at an airshow. It was my first time at an airshow after many years, so I started talking to him when I saw his camera. With his Canon 6D (a full frame body) and 70-300 non-L, he thought that he had bought a nice combination for shooting planes. That was not the case in reality, he told me. Despite what Canon says on its website and what he believed to be true. He felt a fool.
So anybody saying that the 70-300 non-L is fine may be right when talking about a specific subject, e.g. landscape photography (no AF-speed required) - and then in the range between 70 and 200 mm (where IQ is reasonable) - and then also on a cropped camera (where the low border IQ is no issue). But not mentioning that does not do justice to other real-world experiences, in my honest opinion.
Therefore I can only hope for Canon's sake that this rumors (also) is about a new EF 70-300 IS (nano-)USM with a decent IQ over the whole range but in particular at the long end. Because after all, that is where most tele-zooms are most often used: at or around the long end. And where they are judged in reality."
I think this also explains where the sales of this to-be-expected 70-300 non-L will be high. Note that the folks that semi-pro shoot airshows or BIF, or other niche-parts of action photography, will NOT buy this new 70-300 non-L. These types of photography require a very high keep-percentage and therefore are reserved for highly capable camera bodies like the 7D Mk II, 5D and 1D, together with L-series lenses. But it will be bought by those who want a useable 70-300 lens to photograph kids and animals and anything moving in the real world they live in.
And yes, that would probably mean they can also shoot an airplane if they happen to go to an airshow once a year. But it would be very unwise of Canon to deny them that - as a 'punishment' for not buying FF-body and/or an L-quality lens. Because then, the DSLR could very well be not interesting any more for many.
The first time I heared "my phone takes better pictures there than my expensive DSLR" I did not take it seriously. But I heared it very often. Perhaps this has also reached Canon, because from this forum I understand they have an elaborate system of market research.
I dare writing this so directly because since I wrote the passage that I quoted above, I heave taken every opportunity to ask every person I see with a Canon DSLR and a zoomlens (friends, collegues, strangers I see on holiday, in the zoo, in the parc, etc.) 4 things:
(1) what lenses they have (in particular if I see a zoom lens like 70-200, 70-300L, 70-300 non-L, 55-250, 100-400), (2) why they bought it, (3) if they think it is good for what they bought it for and (4) their personal conclusions fot the future.
I did this to 'test' the positive descriptions that were written in several threads about both the old 70-300 non-L and the old 75-300 - often with a lot of conviction.
This has shown me that: it would be very unwise of Canon to give the new 70-300 non-L a slow AF or bad IQ out of some fear boys and girls in Sales have written down. because with slow AF or less IQ than the 55-250 STM, the new 70-300 non-L will be unuseable for what many people want it for and that will lead to more of the frustration about the brand 'Canon' that I regularly heared (although not always agreed with because of a lack of knowledge by the persons that I spoke). Canon will lose many DSLR-users that would otherwise keep buying this and other lenses and (replacement-)camera bodies.
Perhaps Canon has seen this structural scepsis that I have whitnessed and therefore intends to market a lens with a good IQ (which indeed means a big improvement over the old 70-300 non-L) and very fast nano-USM. Despite what some replies in this thread seem to suggest, in my experiende this will boost confidence in Canon and thus the profit of Canon, both in the near as in the bit distant future. Even to the market leader that will a be good setting to cash on.