Rather than using the URL bar, I think it's more likely that people will just open their Uber app, flight booking app, shopping app, etc. I don't think that is an unlikely development.
Additionally, most advertising are about pushing people to buy product like snacks, beer or cloths. I doubt many people really install a Zara or Gap app or put the website in their bookmark.
If we assume that different search queries are better served by different engines then I wonder if it's not possible for someone to develop a "thin" search engine that would do semantic analysis of the query and then redirect it to one or more sites, or show results side by side...
http://venturebeat.com/2015/12/22/google-is-reportedly-devel...
This is why I have mad respect for Zuckerberg. He's willing to place gigantic bets (Instagram/WhatsApp) when and where it matters.