How would a temperature profile in wall change if the rate of heat transfer increases
If the heat transfer in fluid 2 is fast, the thickness of the boundary layer wall - fluid 2 is very small (the 'not so linear' part of the temperature profile on that side) 

One can then approximate that the temperature of fluid 2 directly at the wall is equivalent to the bulk temperature. 

So the temperature profile through the wall would be steeper, indicating a larger overall heatflux - see it as a self fullfilling prophecy: fast heat transfer will allow you to transfer heat faster