At first the box may just remove streaming apps, leaving YouTube and media player functionality, but eventually theres a software update that comes and fully bricks it. As I learnt the hard way.
If you disconnect it from internet you can keep the media playing, thanks to the Roku Media Player app, which is what I've done with my second box.
Alternatively you can try blocking domains to prevent bricking and keep streaming apps working.
Shame to kill off perfectly good hardware.
The Fetch TV replacement is trash, IMO. Constantly streaming content, hard to find apps, audio stutter with version file formats.