That statement is very incomplete, as it entirely ignores the role of software. As things are now, you will see no performance difference between the dual core S4 and the quad core S4 (except in theoretical benchmarking apps designed to stress test multithreaded performance). That isn't changing anytime soon.
The best shot at exploiting any performance gains to be had from a quad core CPU's would necessitate Microsoft specifying a new chassis spec for WP9 mandating a quad core CPU. As long as dual core CPUs are part of the WP8 market, developers won't be taking steps to exploit quad core CPUs to any significant affect.
WP9 is 64-bit and will not be ready till 2014 Q4 when ARMv8 is ready! Till then we are suck with 32-bit ARMv7 software.
Like it or not 2013 is the year of the Quad Core phone's! WP8 can do up to 64 Cores'......with the new Qualcomm Quad core Snapdragon 600 and 800 SOC out very soon Microsoft will use S600 & S800 with there upcoming updates to WP OS with Windows phone 8.1 & Windows Phone 8.5 this year.
Don't be surprised if some WP8.5 software won't run with our WP8 hardware. Remember it's not just the CPU there changing...the GPU as well!
Moving from Snapdragon 4+ to Snapdragon 800:
- CPU Krait 2 core to 4 core
- GPU Adreno 225 to 330
IE10 is GPU hardware accelerated! Now with the new Adreno 330 is going to be crazy fast
I Love new hardware but the world hardware seems to be moving very fast and software is playing catch up.