I tested https for a while and I decided to switch back to http.
Knee-jerk reaction, stick with https.
You shouldn't expect to see an increase in the SERPs, but Google has plainly said they were moving to get all sites to be secure. Adding HTTPS was never about ranking better, it was about avoiding ranking worse after a grace period for sites to get HTTPS
. When everyone has had plenty of time to get an SSL cert, Google will change the ranking and HTTP only sites will drop, with some exceptions. Google's announcement was the beginning of that grace period
I'm expecting in the near future that HTTP sites will be demoted and HTTPS sites will stand their ground.
This is similar to adding RWD to your site so your site continues to rank on mobile search vs. being demoted. People wrongly think RWD or HTTPS will boost rankings when in reality it's vaccinating your site against inevitable demotion if you don't do these things. Why is Google pushing SSL?
HTTPS is a pretty good trust factor plus it's one of the ultimate anti-spam tools as web spammers won't be able to get or maintain SSL for all their sites, if they can get it to start with.
In the future HTTP may be the same as web spam, you may get a yellow warning page "UNTRUSTED SITE" when clicking on HTTP links
just like the red warning pages for malware today. I could see that happening in as little as 24 months as the web transitions to HTTPS.
People running serious sites will get secure certificates and pay the fees to make sure their visitors/customers know that they are a legitimate secure site.
Compare that with web spammers or link schemes where the very business model requires being on cheap and anonymous hosting. HTTPS is the exact opposite.
Those that don't go through the secure cert verification process will be assumed they're possibly trying to hide something so they'll be hidden in the SERPs.
IMO many websites will drop like rocks whether it be they're really spam sites or just lack the funds to support an SSL cert. Those that rank will have just a little more cash to spend than those that don't. I expect there will be some wildcard SSL hosting sites out there for those that can't afford SSL which the spammers may also use and defeat the whole process. Google might demote wildcard SSL because of that in the future which will harm some legit sites using it for their subdomains.
The bottom line is spammers won't rank without SSL and SSL forces them out into the public to be tracked. The expense and time involved to keep swapping SSL certs will drive the spammers, and some collateral damage, out of business.
It's just another move in the big online game of cat and mouse being played out between Google and the gamers.
Just remember, when Google tells you to do certain things like HTTPS or RWD it's not to rank better but to avoid ranking worse after a grace period.