As of today, you are good. But, google is implementing a new rule where you only NEED ssl if you are accepting private information and/or user passwords. That rule goes into effect at the end of January, 2017. Otherwise, this is not true. You will NOT be de-indexed if you do not have an ssl.
Now, that being said, internet security has been picking up some steam lately. If you keep up with the latest internet news you may have read some articles about a lot of hacking lately (Check out the Russian hacking scheme. They may have been making as much as $3 million to $5 million dollars a day using hundreds of thousands of bots to click their own video ads).
As the number of people who are becoming proficient with computers increases so will the numbers of hackers. More hackers will lead to more talented hackers finding ways around internet security.
So hackers is one reason security will continually increase in importance. The second, and most likely largest reason for security becoming a more important ranking factor is the advancements in cloud computing and APIs
An Application program interface(API) allows you to interact with a software application in a more technical and flexible way. To get an idea of how powerful APIs are go to goolgle's developers apis explorer.
APIS are quickly becoming a huge proponent of cloud computing and virtual computing.
Here's a quick list of some of the biggest cloud computing services
- Google Cloud Console
- Amazon AWS (AKA Amazon Drive or Amazon Cloud Drive)
- Microsoft Azure
- IBM Cloud Computing
- etc...
Each of these platforms offers smaller companies and even individuals an immense amount of flexibility and power to interact with both the cloud computing software and, depending on how you utilize the technology, the end users personal information.
As amazing as this type of technology is, there are new barriers and vulnerabilities to overcome.
The two barriers biggest are
- Protecting End Users Privacy
- Possible security vulnerabilities to the corporations software due to the amount of access APIs give developers.
Both of these fall under security problems. And as this type of technology grows, which is inevitably will, the security measures will only increase.
So, to round it back to answering your initial question. Right now, no you will not be de-indexed for not having an ssl. BUT, having an ssl certificate is a direct ranking factor by google and will most likely become more and more important until it is eventually required. So, in conclusion, as long as you are not accepting user passwords and don't accept credit cards or private information directly you should be good. But, for how long this will hold true is questionable