No one can argue that one has to niche down in order to succeed online. Perhaps, even niche down a few times.
If everyone is niching down, then everyone is starting to do the same thing. That is, if people are niching down and not selling "socks" and instead are selling "men's sports socks", then that market will become just as saturated. Perhaps not as saturated as 'socks', but if everyone is filtering down to more specific niches, they too will be (some already are) saturated.
Or let's say you have a site that focuses on 'stress management'. As soon as your 'tribe' members learn how to manage their stress, you've lost them. But, if you have several sub niches under the self improvement umbrella on your site, you have a better chance on keeping your tribe.
I'm suggesting a 'contrarian' approach. Just as a contrarian buys at the worst times, I think it's worth the effort to go bigger.
Now I know that it will be harder to get organic traffic etc...but think about this..
1. You won't have as many competing sites because everyone else is niching down.
2. Tribes get bored and they move on.
3. People grow, change, and like 'new stuff'. If you have the same old same old, they might move on. But if you have a variety of 'stuff' or 'advice topics' your tribe can grow with you.
4. Create your own niche. By combining some sub niches, you can carve out your own spot.
5. People like Jeff Goins, Leo Babauta, sites like Upworthy, Buzzfeed, Viralnova, Amazon, and gurus like Tony Robbins aren't confined to one specific niche.
I'm not saying that this is the best way to start a business online. I'm just saying that it's worth the thought.