What they could do is something the other guys are institutionally unable or unwilling to do: build a proper user agent for power users. Radically transparent, trustworthy and extendable up the wazoo. With footguns and everything.

That gives you a comfortable moat, a raison d'être and a stock of rabid, technically inclined fans which spread the word for you to their friends, family and coworkers the next time Google tightens the thumbscrews again.

Basically: repeat what happened the last time when it was Firefox vs. IE, twenty years ago.