How do you balance NPC combat in a game. I'm not going to answer this but I think I understand some of the problems FD face.
Please remember that nothing here is fact, only my personal opinion and ramblings.
One way is of course what Frontier are already doing, using a skill indicator (combat rank), but arguably the number of variables are huge.
One way of taking this further behind the scenes is by giving every attribute that influences combat a value and then adding that up to a combat value that is used to select a suitable opponent. This could take your ship and configuration into account, but I imagine that it would get messy an complicated real quick in ED given the number of possible ship variations and modifications.
The problem FD has as I see it is:
A player who is Elite in combat can fly different ships, take on different roles and do different things in game.
One minute he is a bounty hunter, the next he is a trader in a trading ship and next he is exploring without weapons or even shields. After that he is doing missions in a multi role build. Should the game take all this into account and dynamically adjust the NPC combat AI to all the possible situations. Is that even possible?
In game design you create game loops and ideally an in game action must have a counter action so that an outcome is not given.
Putting a player in a situation where death is certain is bad game design.
The level of complexity this brings will ultimately mean that there will be situations where a very skilled player with the best equipment will find the game less challenging, and this is especially true for a sandbox game where all players, regardless of skill, share the same playing field.
There are elements in game to cater for this, LOWREZ, HIGHREZ, HAZREZ is one, low and high intensity CZ's is another. This might not be ideal, but I personally can't see how they can cater for every situation and every variation.
Personally my current issue is that there are still situations where the outcome is given. This is mainly related to missions and NPC wings, mass lock and aggregation of heat weapons from multiple ships where I have found escape impossible and death certain even in a well fitted multi role ship (I have mentioned this earlier in this thread). These are mostly edge cases, but none the less frustrating. How to solve this to everyone's satisfaction, I don't know.