Leaves look like weigela, flowers too dark for Abelia x grandiflora. Can you show a closer view? Otherwise, yes, since the one part is still viable it seems possible it will fill back in. Why, specifically the rest died would be pertinent to future outcomes. For instance, if it was killed back by cold it will probably happen again.

the simple rule.. is dead stuff is always pruned out.. back to a live stem .. one with leaves ..

once done.. then you decide if you want to keep the rest ... or be done with it ...

and.. with this much damage.. a little follow up pruning.. to get it back to a form you like.. would also help ...

ID would be nice.. with a better pic.. but the rule wont change.. for the type of plant .. we simply dont want to look at dead stuff ...

ken