Facebook search, in its current form, is rather limited in scope and not even very good at the few things it's supposed to do. As a result, few people use it and even fewer care whether they show up in Facebook search results or not. Only a "single digit" percentage of users had it enabled, Facebook said.
With Graph Search, all that is going to change. Facebook's Graph Search may be the next big thing or another dud, time will tell.
There's certainly potential in it, but it depends on the execution and on whether it's something that people want. No matter what, Graph Search is not going away anytime soon.
It's only available to very few people now, but it will be rolled out more widely. If it's good, people are going to start doing searches on Facebook a lot more and your profile will end up in results a lot more often.
Currently, without the Graph Search, the vast majority of people that stumble on your name in search results are either looking for you, or are your friends or friend of friends. Up until a few weeks ago, you could even block those people from finding your profile through search.
With Graph Search, anyone in the world will be able, or rather more likely, to find you, based on your publicly available info, if they do a specific enough search, even if they're not looking for you particularly.
In essence, your public info is now a lot more public. Most people think their Facebook stuff is private not because of privacy settings, but because it's hard to find, "privacy through obscurity" if you will.
People know their profiles and likes are visible to the world, but as long as someone isn't looking for them specifically, they think they're safe. It's not entirely true now, of course, but it's going to be even less true when Graph Search becomes popular.
This is why the ability to opt out of Facebook search would have been a lot more useful with Graph Search and this is exactly why Facebook removed it.
You can still remove yourself from results in "other" search engines, so you can keep your profile out of Google or Bing, just not out of Facebook search. Someone actually looking for you won't find you on Google, but someone who's not looking for you will find you in Graph Search.