If you define "crumbling foundations" as "a dependency that is unreliable in the long term", then your conclusion is circular. Of course no long-term products will be built on crumbling foundations, because if a technology stack has long-term successes then, by your definition, it is not a crumbling foundation.
I think the other posters are using a definition of "crumbling foundation" as "one which most engineers hate, which slows them down through excess complexity". And by that definition, almost all successful projects are built on crumbling foundations, because the fact that the project was successful leads you to add features to it, and adapt it in ways that the original architecture didn't anticipate. This process only ends when the software becomes so complex that all further attempts at modification fail, at which point everybody hates the codebase and it is, by pretty much any definition, a "crumbling foundation".
I think the other posters are using a definition of "crumbling foundation" as "one which most engineers hate, which slows them down through excess complexity". And by that definition, almost all successful projects are built on crumbling foundations, because the fact that the project was successful leads you to add features to it, and adapt it in ways that the original architecture didn't anticipate. This process only ends when the software becomes so complex that all further attempts at modification fail, at which point everybody hates the codebase and it is, by pretty much any definition, a "crumbling foundation".