Technicalities aside, TS is being pushed by MSFT in their SaaS custom components, and that right there will keep it relevant a while. MSFT is known for changing names a lot, but not for killing technologies.
After over 5 years of writing TS, I have had to do plain JS sometimes, and it is scary. It feels like walking blindfold. I’m spoiled.
Grandparents! They signed up for this when they had kids, or at least it’s common practice where I live.