While we might have superior tools within the parser for PC, such as real time telegraphing of data that happened during the fight, the core functionality which is essentially a glorified calculator will remain exactly the same which is all we really need in most cases for the general player base. Everything else is icing on the cake for the min/maxers and technical people. As long as the core functionality is updated nothing else really matters too much.
So i don't get what you mean by scaling difficulty? Might be the way you worded it for my sleep deprived brain
Assuming you mean scaling difficulty of new content based on parsers, no it won't SE will continue to design content based on their decisions as they have always done. AKA Lv + ilv and whatever they deem suitable as an average DPS for that combination. A parser won't affect that as they do their own internal testing and likely won't change their method from what they do now.
If i'm wrong please elaborate on that