Until http/2 comes around? I've been using it for a couple of months on all our client sites and the standard was finalized last year. It's now available in all current, major browsers.
[1] https://blog.cloudflare.com/cloudflares-impact-on-the-http-2...
That users aren't connecting to http/2 web sites is no indicator that http/2 is not available.
If 47% of all CloudFlare users are not connecting via HTTP/2 (even though it is supported server side), I believe it means that those users do not have client side support (or are behind a proxy, etc. which doesn't allow it).
At the end, if someone is thinking about making a website which would be much slower for non-HTTP/2 users then right now it means around 47% of their users.