Lesson for all of us (customers of SaaS companies): never depend of VC backed non profitable companies for critical components of your infrastructure or business processes. Always build on tried and tested open source software.
Open source may be safer than proprietary software in that regard, but it's still not a guarantee. Still far preferable IMO.
No, but you can maintain it yourself, or hire people to, or worst case you can at least run it and accept the bugs. You're not going to just get in one morning and find out they've turned off the servers and all the stuff you had in their system is gone.
The culture that has birthed these mongrol JS frameworks worships shinyness and novelty. These are naturally temporal qualities. It's why for almost no one does it make sense to buy a mid-range Mercedes/BMW. You always lease because you know it will fall apart after the warranty period.