Full Idea
String theory has now been incorporated into Ed Witten's M-Theory, which is a mathematical framework that lives in 11-dimensional space-time, involving higher-dimensional objects called p-branes, of which strings are a special case.
Gist of Idea
String theory is now part of 11-dimensional M-Theory, involving p-branes
Source
New Scientist writers (Why the Universe Exists [2017], 09)
Book Reference
New Scientist writers: 'Why the Universe Exists' [John Murray 2017], p.169