Is it possible? Sure, why not? If you believe your mount is the best, you need to flex those muscles every now and then.
While it is close to the RF 50mm f/1.2L USM in speed and focal length, I imagine an RF 60mm f/1.0L USM would provide a very unique look to photos. Throw in defocus smoothing and you could have something special.
For now, this is a [CR1] rating, but I will do some digging to figure out the validity of this rumor.