The biggest problem now facing the web is many millions of websites which are not running secure.

With browsers and search engines putting web security high on their list has made it so that millions of websites now need repairs.
Browsers have recently made it so web forms and not be filled in if the page is not secure.
They will go even further soon which will make websites that are not secure lose much traffic.
Search engines will rank non secure sites lower.
Although DV SSL certificates are now free by most hosting companies this alone does not solve the problem.
Sites that were not designed for security will have problems such as mixed content and proper redirects.
Most web designers that are not well skilled used full urls for links, images and other items requiring a url.
Best practice is to use relative urls as this neither points to a secure or non secure location.
A relative URL would be as follows for an image as you would put /images/imagename.jpg
This not only solves the secure problem but also solves the speed problem as relative urls are faster since they pull the request from the server directly.

Mixed content

This is a problem when includes, links or images are pointing to non secure urls.
This requires a tech to go over the entire website to fix all the urls and links on every page.
For those using Wordpress or Joomla this is a smaller problem as in most cases it's a quick fix.
Custom built sites on the other hand can require much work.
Problems can be in web pages or in CSS files and redirects need be created to make the secure page the default for all pages.

Advertisements add to the problem

Banner exchanges and ads are a problem also.
A banner ad which is pointing to a non secure page hurts your site.
Any thing on your site which has a link to a non secure site will cause your site to show as not secure!
Most banner exchanges, if not all of them, are not secure and worse have ads which point to non secure sites.
I have often had popups complaining about ads running on Skype as not secure!

How far the they go with this new direction taking place on the web remains to be seen.
One thing is for sure is having an SSL installed on your hosting account and having the secure url as a default is now a requirement.
Along with that is also that you must be sure all content on the site is also pointing to a secure url.