I haven't had the Flash plugin since 2012 and only a few couple of times I've encountered something I wanted to use which required Flash since when I stopped having Flash. In every case where Flash was required I simply Googled the relevant keywords and found what I was looking for provided by other non-Flash sites.
If you use Livestreamer and an IRC client, you can run Twitch streams outside your browser. That's what I've been doing - I haven't had flash installed since that cross-platform RCE bug late last year.