Oh, wait, I see now, the pic was sideways.
When was the strike? It looks pretty well calloused.
I you haven't already, do the usual things to encourage health and reduce stress, RCX, mulch, regular watering, root invigoration...
Probably have to remove the dead lead but that's going to leave balance issues. I can't tell if it has targets but if not, leave it until you know the if the tree is recovering or continuing to decline.
I think removal has to be an option, it's in a bad way. It would suck though.
What's the rainfall status around it. We're in full-on drought and lots of trees, including pecans are retreating and dropping foliage. Every blackhaw I've seen has half brown leaves, every dogwood is shriveling and the leaves are like paper. Most folks are missing it because the drought is only now making news.