“They certainly have the money to keep pace with Chrome”

This point has been made before. But Chrome is a moving target. I actually am skeptical that Apple can spend more money on WebKit than Google can on Blink.

The way Chrome rose to prominence was by implement brand-new web standards faster than anyone else. If the question is only, “what engine supports the most websites,” I suspect Chrome will increase their development pace in order to try to extend their lead.