What replaces the Schwarzschild singularity in quantum gravity?
In plain words
General relativity predicts that everything inside a black hole ends at a singularity after a finite time. A quantum theory of gravity should replace this with something finite, but no calculation shows what.
Precise statement
In a UV-complete framework, for example AdS/CFT for large AdS-Schwarzschild black holes, identify observables sensitive to the $r = 0$ spacelike singularity (such as the light-cone singularity of boundary correlators on a secondary sheet found by Fidkowski, Hubeny, Kleban and Shenker in 2004) and determine how finite-$N$ and finite-coupling effects modify them. An answer is an exact or controlled computation of such an observable showing whether the singularity is smoothed, replaced by a bounce, or remains an endpoint of semiclassical time.
What would settle it
A non-perturbative computation of a boundary observable that probes the singularity, carried beyond leading order in 1/N.