Let me answer that one question, though:
> Can you say the same of Typst?
Of course I can't. I'm not claiming Typst, a 4(?) year old project, is more stable than LaTeX. What I can say is:
* Typst has given me an impression of thoughtfulness and robustness from the start.
* It solves the many pains I always had with LaTeX (and I have written a Ph.D. thesis with LaTeX — not the most typographically demanding, but still, I'm not a novice)
* It's not a huge deal for me if my documents don't compile 5 years from now, or if the tool I use to compile them needs some reasonably standard, if not minimal, toolchain to itself compile. Sure, something as portable and stable as TeX would be nice. But if I retain 1. the compiled document itself, which is what I care about first and foremost, and 2. the document Typst source, which IMO is much more readable and understandable than LaTeX source, I personally consider that sufficient preserved information, even if the tool that was used to go from the later to the former was lost/rendered unusable.