Nice ideas, but I have different ones.
I think that we can have games that have absolutely no level scaling, only different zones with pre-defined danger level, maybe a little bit randomized, and the danger level of those zones can be dynamic, and in each play-through can be different from other play-throughs.
In each game, you can start in different places, depending on your choices in the char-gen phase, and that place can be marked as newbie area, and an intelligent engine can start from that place and mark the different zones with different difficulty level, each zone can have a pre-determined danger level depending on some factors, one of which is the starting place of the player.
Other factors can affect the formula of defining the danger level of different areas, and a bit of randomization can enter that formula as well, the place for each major quest of the main quest can be defined in this phase as well, and can differ in each play-through.
In fact a real time engine can check the parameters of each quest line and decide where to start it and where to continue it's events, in the fly, and each play-through can be as different as the designers want, or they can decide that there needs to be some fixed elements for all the play-throughs.
In the end, the enemies and loot on each zone are scaled to the danger level of that zone, but can be selected from random lists scaled to the difficulty level of the place.
The players could be warned about the difficulty level of each area before they enter that area, for instance by the mood of that area, smoothness or harshness of the weather effects, the music theme, the signs of a previous massacre, and so on...
And they can decide if they like to take a risk and enter that area, or leave it for a later try, when they are more developed and prepared, but for sure they have to develop their character to higher level, before they could beat the main quests.
Each quest line can define a difficulty range for their setting, the theme of their setting, the required roles, and item types, and so on.., so the engine would prepare them in the difficulty level of their choice, and in the right setting, so that they would fit right in.
And when I say that the enemy and items should be scaled to the difficulty level of an area, I mean if an area is marked as a newbie area, then the loot and enemy level should fit for a newbie character, but there should be a really minimal chance of finding higher level loot there and in the stores of that area.
But when a place is marked as mid level area, then there should be from low level to mid level monsters, and from low level to mid level loot, but mostly low level ones, and a small chance of finding higher level loot.
And this formula can continue for higher level areas as well.
But there should always be hand placed monsters, items, setting, scenery, life, letters, and stories for each area as well, so that each are has a character of each own and be unique and individual.
This results with a dynamic game and land which would be totally different in each play-through, but each place has its individual uniqueness, and there is absolutely no level scaling at all, but all the places feel natural, and the players can decide for themselves if they want to stick to areas that they can easily survive or risk the more dangerous places for a chance of finding better loot earlier.
And in this setting, performing any task should yield to a skill progression, depending on the difficulty of that task related to the level of the player's related skill.
So if you kill a low level monster when you are low level with a blade, you should gain relatively adequate blade skill boost, but doing the same task when you are an experienced swords-man should result in much less skill boost, so that you have to find foes that are more appropriate for your level.
And each time you hit a foe, you should gain experience scaled to the amount of damage you inflict but should also depend of the level of your opponent scaled to your skill level.
So in the end I say that we can have a really intense but hugely rewarding and satisfying experience which is very dynamic and never the same, but have absolutely no level scaling, and in such place, players really can feel that they are growing and broadening their horizons, and feel greatly satisfied with each conquer, and each chain that they break.
OK, that's all.