Perl never had a monopoly on a runtime environment with an install base of pretty much everyone who owns a computer, tablet, or smartphone. Sometimes it's not about engineering principles.

If native mobile apps end up de facto replacing the open internet, that could change, of course. But I hope the internet remains, warts and all. And as ARM chips improve, and DOM APIs are expanded, and JS engines become more efficient, and the HTTP spec is ever more optimized for web applications, I think in the end the browser will survive.