ArcObjects is definitely going away in the longer run, with the retirement of ArcMap / ArcGIS for Desktop.
So your best bet, if you still need to automate stuff and don't have really advanced requirements relying on very specific ArcObjects functionality, nor need really complex UI designs, is to go with Python / ArcPy as much as possible for any development.
Python and ArcPy are available in ArcGIS Pro as well, so this is future proof. There is a difference between ArcMap (Python 2.x) and Pro (Python 3.x), but this difference is quite easy to overcome, and besides upgrading the code to be compatible with Python 3.x, you can also write code that will work in both if you test for the application name in your code. I have done that with a complex toolbox with many tools, it now runs fine in both ArcMap and ArcGIS Pro.