You'll have eventually have significant costs because to be viable you need generate 20M+ pageviews/month to make a good living with the sort of CPM rates I expect a site like this to get. With realtime updates and active chat threads, you'll need a bit of server horsepower to keep things moving.
I think it's a longshot because you're entering a market that relies on massive network effects to create a few dominant players, and becoming a dominant player is tough. Plus, there are already "close enough" sites that people are happy using. Due to network effects, you're going to have a tough time pulling people over to your service when their friends are on Facebook/Twitter/Reddit/etc.
To summarize, you're entering a competitive space and your revenue plan sounds shaky. On the other hand, no one ever accused me of being a visionary.