TITLE: Internal categories in simplicial sets
QUESTION [19 upvotes]: Is there a model structure (or more generally a homotopy theory) on the category of internal categories in simplicial sets, which presents the theory of $(\infty,1)$-categories?
Note that this category is closely related to other known models for $(\infty,1)$-categories.  For instance, any simplicially enriched category can be regarded as an internal simplicial category with a discrete simplicial set of objects.  And any internal simplicial category has a bisimplicial nerve which is a Segal space.  One might hope that these functors would be part of Quillen equivalences.

REPLY [17 votes]: It appears that Geoffroy Horel has solved this problem completely:

Geoffroy Horel, A model structure on internal categories in simplicial sets, Theory and Applications of Categories 30 No. 20 (2015) pp. 704–750 (journal page, arXiv:1403.6873)