One major issue perhaps is the cost and complexity of setting up SSL certificates for small mom and pop websites but Mozilla and others hope to have this covered via initiatives like Let's Encrypt, which promises free certificates that work across all browsers without usage restrictions.
There's pretty broad agreement that HTTPS is the way forward for the web. In recent months, there have been statements from IETF , IAB , W3C , and even the US Government  calling for universal use of encryption, which in the case of the web means HTTPS.Via: Phoronix
In order to encourage web developers to move from HTTP to HTTPS, I would like to propose establishing a deprecation plan for HTTP without security. Broadly speaking, this plan would entail limiting new features to secure contexts, followed by gradually removing legacy features from insecure contexts. Having an overall program for HTTP deprecation makes a clear statement to the web community that the time for plaintext is over -- it tells the world that the new web uses HTTPS, so if you want to use new things, you need to provide security. Martin Thomson and I drafted a one-page outline of the plan with a few more considerations here:
Some earlier threads on this list  and elsewhere  have discussed deprecating insecure HTTP for "powerful features". We think it would be a simpler and clearer statement to avoid the discussion of which features are "powerful" and focus on moving all features to HTTPS, powerful or not.
The goal of this thread is to determine whether there is support in the Mozilla community for a plan of this general form. Developing a precise plan will require coordination with the broader web community (other browsers, web sites, etc.), and will probably happen in the W3C.