This exists in the ArcMap editing environment and is super convenient as it allows you to copy features from one feature class (especially complex polygons/lines) to another in a relatively quick manner. I've tried using copy/paste in ArcGIS Pro 2.0 and that doesn't seem to work. There appears to be a custom add-in for the "Replace Sketch" feature, but I can't figure out how to get it to work.
I guess I'm just hoping that this can make it into a future release of Pro or perhaps someone can tell me how to achieve this in the current version. And "Replace Geometry" is not the same as you first need to have an existing feature and then manually draw/trace features.