Since the 10.3 release, I have seen many post on GeoNet related to the deprecation of the SDE Command Line tools. There is a lot of confusion as to usage of the tools against 10.3.x or newer geodatabases.
I thought it might be helpful to have a single location on GeoNet (if that is possible) to post, add ArcGIS Ideas and other information related to the old SDE Command Line tools and replacement tools and/or workflows. This might also clear up some confusion and "double posting" of the same questions in GeoNet.
As always, if you have more detailed questions or need a more "definitive" answer, I would recommend contacting Esri Technical Support and opening a support case with them to review your specific use case and information.
Here is a list of articles for your review in no specific order:
Migrate from ArcSDE administration commands—Help | ArcGIS for Desktop - Tools that are currently available at the current release
Recent Proceedings - Presentations from the 2015 UC Conference
Please post in the comments any other articles, blogs, post, information, etc. that I might have missed. Hopefully this will be central place for this information and facilitate the conversation forward.
Now let the fun begin!