There used to be an electronic repair shop in every neighborhood. These were small businesses that would be able to diagnose and repair faults in random electronic devices.
I wonder if at one point this problem of cloud services disappearing will become widespread enough that we'll start to see businesses that will take your bricked device, flash their own firmware to it and provide their own, generalized cloud service as a replacement.
Obviously reverse engineering each device and making a custom firmware would be a large initial investment, but maybe at a point where just about every trivial thing will depend on a network service it would be economically feasible.