It's getting complicated here. Likely robots will be connected. This makes them perfect for spying and sabotaging. US cannot let China control them. Likely EU will do the same.
If not connected they can be used for numerous criminal activities. Stealing, selling drugs on the streets, etc. Armed robberies will be impressive.
So, my guess is robots will be connected, and this will be enforced in software and, may be, hardware. To the point that makes them almost unhackable. However it should be possible to take the frame and low level electronics (like motor controllers), and fit it with custom high level compute module and software. It will be just quite a lot of work. Still can be done by community of enthusiasts.