Something that could help is perhaps a choice that examples should work in (e.g.) Firefox recent.x on ubuntu, then provide a VM and archived version of firefox.

Something that could help is perhaps a choice that examples should work in (e.g.) Firefox recent.x on ubuntu, then provide a VM and archived version of firefox. Put it on a platform that archives things with C/LOCKSS and get a doi, then although you're not expecting people to use it on a daily basis, it'd cover several "worst case" kind of scenarios. Of course that's not completely permanent, but would perhaps provide some more safety.