We're told by a very good source that Canon will finally address the 50mm focal length in 2018. There are apparently two prototypes currently being tested by select photographers.
We're told one of the lenses is an EF 50mm f/1.4 IS USM, which was likely developed alongside the brand new EF 85mm f/1.4L IS USM. We were not told what the other 50mm prototype lens was.
The announcement is slated for some time in the first half of 2018. As always though, lenses come where they're done and ready for production, not when the marketing people want them to be announced. Therefore, delays are always possible.
To be perfectly honest, we don't like reporting about 50mm lenses, as we've been burned a few times in the past.
The same source did mention that a previous design for a fast 50mm lens was scrapped due to do some new technologies in design and manufacturing that Canon utilizes now.
We're wondering if Canon will do the same thing with the 50mm that they've done with the 85mm and that's keeping the f/1.2L version current while adding the f/1.4L IS to the lineup. It wouldn't shock us to see the nearly 25 year old EF 50mm f/1.4 remain current as a value option. We think a 50mm f/1.4L IS would fit nicely in the lineup at around $999 USD.