Ok, in this player's humble opinion this does not de-value those with existing AA's. Why? Because you have had use of those AA's and have already been able to extract value from those AA's.
From what I've read (I only got through to page 4 last night) the curve is adjustable over time and will always be adjusted to return to normal somewhere in the newest expansions' AA count.
Keep in mind they have already changed how you are gaining AA exp to be based on the con level of the mob. Even con mobs give the same AA exp at every level. So a level 55 person fighting an even con will gain the same exp as a level 80 who kills an even con. This is the "base exp" that they reference in that thread.
As an example this is what this means if you want to look at numbers. Again, this is made up numbers as it doesn't sound like they are going to release the actual numbers.
AA count ....... Multiplier
< 200 ............ 5
201 - 400 ....... 4.5
401 - 600 ....... 4
601 - 800 ....... 3.5
801 - 1000 ..... 3
1001 - 1400 ... 2.5
1401 - 1800 ... 2
1801 - 2300 ... 1.5
2301+ ........... 1 (this is normal)
A new expansion comes out and adds 500 AA's and the scale could be shifted to be:
AA count ....... Multiplier
< 200 ............ 6
201 - 400 ....... 5
401 - 600 ....... 4.5
601 - 800 ....... 4
801 - 1000 ..... 3.5
1001 - 1400 ... 3
1401 - 1800 ... 2.5
1801 - 2300 ... 2
2301 - 3000 ... 1.5
3001+ ........... 1 (this is normal)
If you are a max AA player, the fact that the newest AA's will still be earned at the same rate as before this change does nothing to devalue your AA base. You will still have the newest and best AA's. And if you go earn the newest 500, you will have earned them at par with everyone else and have had use of them. Anyone who wants the newsest and latest 500 will always have to earn them at the same base rate as you. A year later if someone comes along and then earns those 500 at a 1.5 accelerated rate then you still have had the value of having the AA's for the previous year. Once they catch up to the newest set of AA's they too will only earn the latest and greatest at a normal rate.
As I see it this is a *GREAT* move to help balance the player base and reduce the gap of the "hard core raider" vs. the "casual player" (just as the resetting of armor values in SoF is doing). I also see it as a great boon for the higher guilds as it should help increase the number of people able to meet the requirements for application. Casual guilds will also benefit from players with more AA's and will see an increase in places to exp or smaller targets to kill (AA's are a huge part of raid encounters).
Overall I believe this will help encourage new players to join and old players to return which in turn will only help server populations. I have plans of playing for many more years still so this is good news on that front.
The only people who I feel will be hurt by this will be those with an overly accute and sensitive e-***** problem. Perhaps this is just what the Dr. ordered.