I just fail to see why this new 50mm will be a problem. We will then have:
$125 or so --> 50 F/1.8: nifty fifty
$350 or so --> 50 F/1.4 (sort of) USM: a great lens for the dollar (like the 85 F/1.8:)
$800 or so --> new 50 F/? IS USM
$1300? (I have forgotten) --> the 50L F/1.2: the high art / portraiture lens, the je ne sais quoi lens, the bokeh magic lens, etc.
That third option is perfectly placed. Many people who feel the L is overpriced or underfeatured will jump at the new offering. I certainly will.
The problem is --- many feel that the 1.4 is the one that needs to be updated...as a 1.4!!!! The market for primes seems to have a clear line in the sand ---the camp that wants a slower lens with IS and a camp that wants a fast lens and doesn't care for IS. The next divide is price - the only way to please both camps is to make a 1.4 with IS but I seriously doubt such a thing would be made available under 1K - or IQ will be garbage from 1.4-2.8.
I just want an optically improved 1.4...or, lets get it on with a 50mmL 1.2v2!
I think some of us (and this is not an indictment) are getting hung up in F/1.4 vs. F/2. It's just one stop. The other improvements -- general overall sharpness, internal focusing, IS, much much faster focusing, better build -- would have me buy this lens at F/2 or F/1.4.
I know I am in the minority here, but I'd gladly give up one stop for all those improvements.
As for 50Lv2, agree. It doesn't even stack up to the current F/1.4 in the corners. For 3-4x the price, it should everything the cheaper one does and more.
I think the camps are pretty evenly divided (because there are a lot of video folks that want the IS). But for those of us hunting for amazing bokeh, f2 is not f1.4!
In my shoes, I want bokeh. If the new 50 is f2 with IS and costs $900, well that just gives me the extra nudge to upgrade my 24-70 to the v2 because that lens is from what I have heard nothing short of amazing!!!! With that lens now out, the only reason to go for a prime in that range is --- bokeh. 2.8 vs 2.0 doesn't let in enough light to make that a wedding lens. 1.4 vs 2.8 though, now that is a difference maker. I can handheld my 50mm down to 1/40th of a second no problem - so with IS I could go down to 1/10th ---but, that won't be of much use at a wedding reception because people are moving.
So yeah, in a nutshell, if it's f2 with IS, that just gives me another reason to save the pennies for the 24-70. But if its f1.4 no IS but improved IQ, corners, AF...then I'd snag one!
Either way, I do think that each variation is different enough to warrant both. But again I really feel that we're talking about apples and oranges here. f2 with IS will appeal to some --- 1.4 no IS will appeal to other...but like I said - if all they release is f2 with IS, I will just go with the 24-70 because the IQ will most likely be better and there is a lot more versatility to the zoom (and no compromise in IQ). And mounted on a 5d3, I have no problems just boosting the ISO to keep my SS at a reasonable level!