If you’ve been putting off switching your site(s) to HTTPS, you might want to consider planning the move.
Google’s Chrome the most used browser now marks any HTTP page as Not secure, if it has password or credit card fields.
Starting in October Chrome will add the “not secure” warning to all HTTP pages when a user enters any data (i.e., contact form, email sign-up and search boxes).
In this phase, it is just a warning, but I would imagine that your conversion rate will drop.
Also, you get a bump in your page ranking from search engines.
The main reason to make the jump to HTTPS is your customer’s privacy. Lots of snooping going on from public WIFI, ISP’s, etc.
Here’s an interesting post from Chris Coyier from CSS-tricks.