I'm a big fan of KiCad but I think Altium has a bigger lead than you give them credit for. Nobody is going to be designing mobile phones, tablets, laptop motherboards or other high complexity stuff in KiCad any time soon. A large amount of PCB design is not high end, but if you're a company that does 90% simple stuff and 10% stuff that requires a product like Altium, you're probably going to use Altium for everything. This may eventually change but it's going to be a while.