(this idea is crazy and will not be implemented in at lesast 10 or 20 years)
Maybe...instead of having difficulty levels, you will have a single, solid AI that learns from the human? Like...if the human uses bad tactics, the AI will "observe" the human, and then will learn from it. If the human uses good tactics, the AI will "obvserve" it and will learn from it.
For example, if the human does an ROP rape, the AI then knows that it is possible. If the human has a tech that is way ahead of them, the AI will strive towards that certain tech that they see being used against them (or a tech that can counter it) and increase tech race. If a human player is using Suicide Galleys...or any other tactics.
IIRC, this is impossible as if this time.