The future of forward proxy servers in an http/2 over TLS world

At the moment, it feels like the functions provided by proxy servers are 
being squeezed out by changes in the protocol.

I can understand the desire for privacy, and we've had the argument 
about whether it should be available to all or not too many times 
already.

However, there are other functions that a proxy is commonly used for 
that are becoming impossible with the direction TLS, HTTPS HSTS, cert 
pinning etc are going.

Whilst I can understand a desire and need for privacy, an ability to be 
able to go to a website without betraying which site you're going to 
(e.g. see https://tools.ietf.org/html/draft-schwartz-dns-sni-01 
<https://tools.ietf.org/html/draft-schwartz-dns-sni-01>) there's 
probably 1 remaining IMO critical bona fide purpose for a proxy which is 
becoming very problematic for users.

Blocking requests.

So, do we feel there is still a place for blocking requests?  Our 
customers still certainly want this.

Currently the user experience is either appalling (generic connectivity 
failure report which wastes a lot of user time), or requires deployment 
of a MitM, which is being squeezed out as well.  We should be able to do 
better, but it doesn't appear to be being addressed at all, and the gulf 
is widening.

I believe we need to put some time into working out how we can allow a 
proxy to block requests without an awful user experience that costs 
users and tech support countless hours to deal with.

This means we have a need to be able to respond to CONNECT with a 
denial, and some kind of message that can be displayed to the user.

It may be that the only way this can be achieved is by the concept of a 
trusted proxy.

Otherwise if the group consensus is that requests should not be blocked, 
we need to deal with the consequences of that.

Adrien

P.s. another key feature is caching, but that is becoming less useful 
anyway.  Customers can often live without caching, they do not tolerate 
being unable to block however.