Indeed. You could have four trains per hour each way on the Kingston Loop at the expense of Shepperton being served by a shuttle from Kingston Bay. Or four trains per hour to Windsor (two via Richmond/two via Hounslow) by operating a Weybridge shuttle from Staines. But how would that hypothetical plan go down with those passengers who appreciate the through services?
In all honesty I think at least for off-peak services this could be preferable if it means a higher frequency of services.
The only downside is, if you've then effectively got everyone changing (i.e. not many people particularly fussed about getting off at Kingston), what's platform capacity going to be like for that many people being fed on and off trains at a regular interval?
Also, how might this affect dwell times of trains?
No its not. If you actually read what TfL/DfT put out for consultation (ie getting public opinion not a cast iron guarantee it'll happen) they want control not to run. That leaves the ability for the same TOCs to run the trains but with difference standards for different routes.
There also the factor of if all these routes do go over to TfL control, simple orange lines isn't going to work anymore on the maps and separate branding is going to be required.
Based on what you're saying, would I be right to assume that what this could mean is that you'd have say, London Overground branding (or some other TfL branding), and TfL setting the standards, but having the day to day operations ran by the franchise holders?