Advice on Focused Niche

I have 3 blogs, all hit with Google. All not focused on just one subject. I make some money still and thankful but it's not enough to live properly. It's peanuts basically. And I'm unemployed so I rely on this. A friend of mine does a certain thing, he has skills in and I did some keyword research and noticed the difficulty etc was quiet low. So his basically an expert. I'm just wondering, do I do a full on focused niche site focusing only on this one subject like a micro niche OR something more broad but still write more on the main keywords but able to branch out to other aspects. I don't like micro niche because you cant expand really but then again, with everything happening with Updates, im thanking of taking a chance.