Why do you think it's getting harder? I think it's always been hard and will continue to be hard. There are a few opportunities and it takes lots of time to exploit them if you get to them at the right time.
In the early days micro isv's were fairly common, and well known. I don't hear much about them anymore.
There's also a ton of new niches opening up, but you need to be aware of them and they don't happen in a vacuum. You can't just sit in your home office that imagine a new niche, you need to surround yourself with people doing other stuff.