I just want a new 50mm f1.4L USM IS.I don't think anyone really NEEDS IS in a 50mm.
I think it depends on the usage and photog profile: An amateur on a tourism trip shooting with a noisy aps-c sensor indoors in low light will appreciate IS when not using a tripod. On the other hand, pros won't need it because fast shutter speeds in my experience beat IS when looking at 100% crops and IS doesn't help with motion blur for event shots. The latter is the reason why the new 24-70 still has no IS.
As for video, Canon obviously cannot make up their mind. They are releasing someting for video usage, but everyone with more experience shooting video seems to use other stabilizer gear. So the market for mid-priced wide angle primes with IS might be very small.
One aspect I like about IS (I've got it on my 70-300L) is not that it enables longer shutter speeds, but that it stabilizes the frame and lets me concentrate on the scene. When using a 50mm on a crop = 80mm this effect is still visible