Not true at all. I've made games for PC and consoles, the PC ones are always the most successful. I can't talk for all developers but every single one I know personally has had more success on PC.
Mobile is fickle. You can't put serious investment into it but it's good to throw little projects onto it every so often, occasionally you'll get a hit that way.
It won't ever be ready, or, it will always be an option. Even with fibre optic you're limited by the speed of light, processing times, there will always be input and display lag. It's more cumbersome (code and infrastructure wise) to send input data to a server, have it process the graphics and music and send that back. As resolutions increase, as 3D/VR becomes popular the bandwidth required would be big. There will be more input data too if tech like biometrics becomes standard. Of course connections speeds will get faster too and bandwidth would need to be unlimited.
Basically there is zero benefit to streaming other than being able to play your game on any device. That can be achieved by other methods (you running your own streaming, a la Wii U or PS4/Vita). Then there's no running costs for the dev/publisher of the game, no maintenance... basically streaming is more work and more costly.
I've seen nothing to suggest that game streaming will replace traditional gaming.
