I have been considering snagging me a 1.4 50mm, so, this to me kind of means i might want to buy it sooner than later. Like many here, I'd much rather have the 1.4 remain a 1.4. There already is a 1.8, if there is to be a new 1.8 upgrade, then just upgrade the 1.8, then give us a real new 1.4.
And yeah, like many others here, I'd much rather have improved optics, and more reliable AF over IS. The 50 1.4 is so light already that I really don't the need or desire for IS.
So it goes, the current 1.4 is $400, which is pretty reasonable for a little lens with good IQ for the price. Upgrade it with IS even with a reduction in aperture - that sweet affordability goes away! Have fun, cause add IS and it will become a $600-800 lens. With the way canon is pricing all their upgrades, without IS the 1.4 would still go up in price I bet, but probably to a more reasonable $550. My bet though is with IS added it will lurk around the same price as the other new primes. Have fun with that!
I know its a little off topic, but, I find it interesting how many of you are willing to shell out more $$$$ for IS on lenses below 100MM in focal length, but also balk at the cost of the 5dmk3 and say its not worth it, marginal upgrade, no DR...etc etc etc. Just saying...