So what would value would your platform provide that people would want to use it? I'd advise looking for a problem to solve and then thinking about the solution from there.
I am solving a problem. It's a video chat platform. The basic functionality I can provide and it's enough to solve the issue. However, I am always thinking ahead... sometimes too far off ahead, but I recognize when something is not currently pertinent. This isn't pertinent currently. However, I still would love do what Google does with their Hangouts, and enable others to create apps for my platform.