ArcGIS Pro is able to generate 2D cache as a tileCache or by using portal for ArcGIS.
It's no longer possible to publish directly to an ArcGIS Server GIS Server.
As a result, caching workflow is slow (ArcGIS Pro is not scalable as it's documented) and we can't have high performance workflow as we had in the past with direct publish/ShareAs to ArcGIS Server and make GIS Server calculate the cache. It's a real mistake when we have to build huge cache that take many days to process.
Please find a way to fix that. If not, customers will have troubles to move forward with ArcGIS Pro and 10.5.