No way the dock will ever have additional processing as the interface to connect the two parts would be hugely expensive and that's not what Nintendo does. I did feel the Dock may have had active cooling so it could be run at higher ghz when docked but that appears not to be the case. If it does clock higher when docked it will simply be because it has no restrictions on power consumption when docked and doesn't have to worry about battery life. I must admit I was surprised the Switch didn't have passive cooling for portable mode and active when docked that seemed like the ideal scenario to maximise performance at low cost.
Still wondering if the recent rumours about the tablet being 1080p are true and if so a VR visor will be available. I wonder if the 720p resolution info was purely a red herring to make people believe Switch didn't have a VR option. It just looks like a brilliant VR system with the removable controllers etc. I won't be surprised if the surprise is VR.