... good stuff...
The big issue here is it takes a lot of dev time to ensure that stuff is living/breathing in the world too.. it can't be static.
To me, there are two parts to the cost associated with playing the game.
- Cost to buy the game / major expansion
- Monthly subscription cost
When I pay $60 initially and $60 for each expansion of a MMORPG, I expect that cost to go towards the development of the game systems and content.
When I pay $15 a month, I expect that cost to go towards the server costs, support, and content growth/manipulation.
With FFXIV and WoW, companies are delivering on the "content growth" part, but many MMORPGs are not, and simply relying on expansions to deliver their content. That being said, even FFXIV and WoW fail to cover the "content manipulation" part of the maintenance.
I believe you are correct in that to deliver on a living breathing virtual world, the content itself needs to age and change. That should be part of the maintenance phases paid for in part by the monthly subscription that customers are paying.
Don't get me wrong, I enjoy old content like Lower Guk in EverQuest as much as the next guy (maybe even more), but that content should have changed and/or even gone completely away over fifteen years ago. Content should not last for ever, and the content should follow the CURRENT story path. If it is truly a living breathing world, your players should not be working on defeating Gates of Discord content when the server is ten expansions beyond that. That story has been told. It's over. The players should be working on content relevant to the current story.
Now how you deal with the power curve is truly a difficult discussion. I mean, what happens when your player base is on the 24th expansion of the game, level 110, and someone picks up the game for the first time? That person is going to be level 1 in a world with nothing but level 105 to 110 content. You can't just make it so they instantly are level 105, and have the needed gear for that content because it makes all the effort that everyone put in to beating the last expansion meaningless. So, you have to have a path for a new player to catch up, and I think that is where the developers have to get creative. You would need to have content to level up and gear up in that is relevant to the current story arc with out making the previous content (that is now no longer available) seem like the those who went through it wasted their time.
I think that maybe the way you would handle this is that you are constantly putting out new content for the level 1 to "current starting level" of the current expansion that replaces the previous expansions leveling path, but in a much smaller quantity of content. In other words, When levels 30 to 50 were part of the current expansion, there was probably 10 zones, 5 dungeons, and 9 raids of content for that level range. Now the game is on it's 24th expansion, and all of that content is no longer available. In it's place, there are 2-3 zones, 1-3 dungeons, and 1-3 raids of content for that level range that are relevant to the current expansion's story. It's a much smaller set of content with accelerated experience and gear progression. The acceleration is not enough to make it meaningless, but enough that a new player could make it through it in a month or two where as it would have taken six months to a year when that level range's expansion was current game content.
TL;DR ... if you really care, take the time to read it. No cliff notes here for ya lol