Off the top of my head, some of LinkedIn's competitors include the likes of:
BranchOut
Viadeo
Bizily
partnerup
company.com
Zerply
If you're looking for what strategies can help to survive, then you should look at how those guys have grown (not only the likes of Viadeo/Xing but how BranchOut have done leveraging the Facebook Platform).
Likewise, you should look at how you can make it "better" in a way that will entice users to join - Zerply mainly tries to do this via better looking profiles. This feature may involve something related to recruiters - maybe even giving them a seperate profile - where they can still find people to recruit for their clients but also so people can use the service for what its for networking.
Infact, you shouldn't limit yourself to looking at how LinkedIn and its competitors have grown - you should also look at other Social Networks and how they've grown as well e.g. Instagram, Badoo, Tagged etc
Similarly, if you're planning on "going viral" and a "great product" then it isn't enough! You need to have a great distribution strategy above anything else.
And if you want to create a "LinkedIn Killer" then it has to be significantly different like how Facebook was to Myspace and for LinkedIn to not notice it (you have to appear different enough from LinkedIn so they simply don't copy the features), in order for you to stay under-the-radar for long enough where you hit a tipping point where, everyone joins your service and you completely take over the market
Create a LI competitor that can get me a new job and I'll use it. In fact, I'll be willing to pay you thousands and the company that ends up hiring me will pay you thousands.
The value proposition is pretty undeniable. The problem is that I doubt that there is really a technological fix to the problem of inefficient labor markets. It would take more social hacking than machine hacking to facilitate transactions.
Some hints at what will work: 1) Don't focus on employees or employers looking to fill traditional roles. Someone with the "expected" resume will have no problem finding a job and the potential employer will have no trouble finding someone like that. 2) Create a platform so that people can interact face to face in real life. The problem with a lot of tech people is that they're too trusting. Most business types want to interact face to face because "that's the way it's done." Why is it done that way? Because you can't record what people say in face to face contact. 3) Don't work with HR or recruiters. They usually don't possess the domain knowledge to think creatively about new endeavors.
Message me if you want to discuss further. I won't invest (at least probably not), but I will be your first customer.
I'm only aware of one American company intended to be a LinkedIn killer, Zerply. Its distinguishing feature is better-looking profiles. It also used LinkedIn auth to import data.