Increasing hotend temperature to compensate for increased filament throughput
I think I see what you're asking, but I think you may be thinking about it incorrectly.  It's really all about heat being added to the system at the same rate that it's leaving.  The heat block is there as a heat reservoir from which the filament draws heat for the glass transition.  The heat in that reservoir is maintained by cycling the heating coil to add energy (more heat) to the systems as it's lost.

In the very local vicinity of the nozzle, the temperature will decrease slightly as it's being transferred to the filament, but because the heat block is massive in comparison to that drain, and because the heat block is a good thermal conductor that temperature reduction is very small.  

I do not know what tolerance and hysteresis are built into the temp controller, but think the variation is likely small.  The difference in additional heat required (more energy into the system) for any practical difference in feed rates (40 instead of 60) is thus likely to be very small compared to the filament cooling experienced immediately after it leaves the nozzle.

Bottom line: the adjustment you would want to make is not to increase the temp, but increase the duty cycle of the heating element to maintain the desired temperature.