Yes, there are many issues in our theories and even our formalisms. All I was trying to is point out, in the simplest way possible, was at least one way we know that GR is "wrong" (incomplete), which is its singularities.
No, we don't know. Most physicists believe it, but that's not the same as knowing. We won't know unless and until we are able to actually do experiments in the relevant regime.
