It's a rival for Formula Ford, and perhaps Formula Renault. I think the intention is for it to be the first car championship once a driver leaves karting. That used to be FFord, but since all the drivers don't want to learn how to drive, and want to have driver aids for their entire career (like paddle shift, wings, electronic dashboards and datalogging), FFord fell out of fashion.
They tried to keep up, but created an ugly beast that doesn't really fix the inherent problems, but removed all the old charm and interest.
Formula Renault is the no-mans land for people that can't get to F3 (budget or talent) most of the time, and I've never taken it seriously as a stepping stone. Sure, there are exceptions (Raikkonen for instance), but they're rare.
So I think F4 will be for ex-karters. Then to F3 or GP3. Then GP2. Then F1.