My point, in a nutshell, was this: a 'sense of progression', as defined by stats, levels, level caps, ...it's meaningless to me. I don't use or need these things to give my character a 'sense of progression.' My character's sense of progression comes from the narrative of my character's journey and the changes in her personality that is a result of that journey. I'm composing a kind of story as I play. That story is what gives my character a sense of progression.
"But, the problem with the Elder Scrolls' current system is that once you hit the skill and attribute cap, there's nothing left to do to progress your character except work on those skills that haven't been maxed out. Thus, having skill and attribute caps encourages players to increase/max-out skills that they probably wouldn't if those caps were removed, which all but forces players to create a jack-of-all-trades later in the game, regardless of whether they meant to or not."
This type of thinking - what my character's skills are, what my character's level is, whether my character is level-capped - is alien to me. I play solely to create a character and to roleplay as that character. I cannot lose a sense of progression if my character is level-capped because I was never keeping track of my character's stats to begin with.
IMHO the best way to keep the sense of progression in open world games, like TES, is to make a world that has a different danger levels in different areas, and there should be always places that are too dangerous for the players to venture into, not that they should level up with the players, but are too dangerous from the start.
Let's say that, half of the entire playable area of the game should be for newbie to low level players, and half of the remaining areas should be for the medium to higher level players, and the rest should be too dangerous for even the higher level players.
There should be no level cap for the players and their skill progression, but the progression should become slower and more time consuming as they advance in their skills, and their levels should be based on their skill progression, visibly or invisibly.
The rate of slowing of the skill progression should be different for each skill for each type of character, so for a barbarian orc, the rate of advancing his magical skills should slow sooner than his physical skills, but as I said before, there should not be a hard cap on any skill progression, and the progression should be visible.
So for any character we should have places that are too dangerous for us to go into, but as we progress our characters, we should be able to conquer more places, by advancing our characters and their gear, finding new strategies, or strategic items, or better companions, and so on...
Those hard to conquer places should not be related to any main quests, but some side quests should require us to be able to survive them, thus the sense of progression would be immense as we can finally complete those quests, by any means, even by running through those areas and be lucky enough to survive the attacks and do the required tasks item and run out.
Because of this, the invisibility spells should not be absolute, and should be removed in favor of chameleon spells that should not have a 100 percent effect, but they should have a power magnitude that would be countered by monsters with higher "Sight" power.
In those higher level places we should also find higher level loots with effects and perks that would give us more strategic options, and help us conquer the even higher level places, but in the end there should remain some areas that would require characters develop for months if we want to conquer them without cheats.
This way the game would keep the sense of progression for any character, for ever.
Does this need higher level content?
Just like Diablo, recycle monsters and items, with new textures, and scales, stats, names, and new http://www.gamesas.com/index.php?/topic/1107940-perks-they-can-make-each-play-through-a-unique-experience, and so on...
Those item perks can be unique, and items with those perks can be super unique, and could only be found in those super dangerous places, and should add strategic advantage to help with even higher level places, but if cleverly designed, they should have limited use for lower level places, and do not affect the game-play experience too much in those places.
OK, that was my two Septims.
Edit: corrections.