From a regular (50 f/1.4)
I'm told for certain that a new 50 f/1.4 is coming this summer from Canon.
It will retail in the $699 USD range.
The same source says there will be one new lens from Canon this summer/fall that is not a replacement of anything current. He didn't have specs at the present time.
There are new teleconverters being tested at the World Cup I'm told. No word on a release timeframe.