If the CO2 line is clogged, then yes, there is the potential for a DIY CO2 pop bottle to explode.
The only real fail safe is to keep up with maintenance, ensuring that the line and/or the airstone does not become clogged.
The airstone probably does not need to be changed, but can use a good cleaning every so often. They will eventually clog if left alone.
In terms of damage; you will have flying pieces of plastic and a large yeast mess to clean up.
The weakest link in your chain of equipment will be the first to go. If (for example) your tubing is not on the check valve perfectly, it is possible that it will pop off, averting a disaster.