An an interesting idea there, since unplacing an item is technically the same action as mining... construction robots able to mine :)

Construction robots can remove objects such as a transport belt aslong as it has been predefined with the deconstruction planner. This is already implemented ...

I believe the way robot ports currently done could be improved by having a feature within the UI of the roboport to allow a user to specify a particular block to pick up and put into storage.
Also the player has the ability to specify what that block should be replaced with(aslong as the block is ...

I had a similar Idea to the one which was mentioned here:
https://forums.factorio.com/viewtopic.php?f=6&t=14575&p=98596&hilit=depleted+oil#p98596

The above thread talks about depleted oil mines notifying the user (Similar to the No Fuel Feature)

I would to suggest a more broader approach in ...