This is a good point, and unfortunate.As more EF lenses get discontinued, the odds of a new 5D Mark V being introduced continues to decline.
I hope Canon replaces this lens in RF mount, and seizes the opportunity to make more improvements than they did with the 50 1.8.
I have mixed feelings about the 40/2.8. I love the FL and got some of my best photos with it. But I don't enjoy using it as it forces me to dig deeper to get great photos. That can be a good or bad thing depending on perspective. I would love an F/2 version with a focus on smooth bokeh and overall rendering. I will settle for the Samyang 45 if that ever comes our way.