As opposed to this, I might consider removing the timer when the player count is significantly below capacity

The timer is not just for sieges or capacity, but also for performance.

If we have 100 players afk, it is typically no different than 100 players playing in terms of performance.

I believe that the increment of duration or even completely removal of the AFK timer based on the player count would be a fantastic idea.

Remove the afk timer as a whole

Also add a veteran queue, I dont like random novice 1 that paid few $ and does nothing ingame have priority over every other player that plays for years now. Imo we deserve atleast a priority queue like donators.

agreed berry, I think that higher ranks should have priority in queue above lower ranks

anything above viceroy could have priority when there is queue (accordingly by ascending rank).

but overall donator would have ultimate priority in queue because that is one of the main purposes of donator ranks on geopol/earth servers

I would believe that adding a priority queue for higher ranks might not be a very good idea for several reasons:

1. It discourages new players to continue playing in the server as it will increase the gap between their "wealth" and the OG's wealth as well as it would prioritize a group of players whose interaction between them are very stable and stagnated to a new group that could bring new variants and maybe even revive the current Geopolitical System.

2. The Mcmmo rank does not efficiently reflect the player's presence on the server as it's contribution towards the community. There are many OGs that are still lower ranks such as Colonist or Colonizador, while some "newcomers" have already achieve high ranks such as Viceroy, Duke or even Archduke due to their quick grinding and abit of luck.

3. The Donator's priority queue is due to it's contribution of maintain the server up and running, while the Archduke and Exclesiour player are unable to provide such income.

With this in mind, one might suggest that instead of the McMMO rank the time of entry to the server could be a solution to maintaining this new "veteran queue". Nevertheless, such would also be inefficient as many OG have gone to several account swaps.

Gold, if we would to prioritize the time of entry or even the playtime of each player towards an queue, it would greatly discourage the newcomers besides the well known wealth gap you mention. Like you also mention, the only rank that is understandable to have an priority is the Donator due to their active contribuition towards the server and it's maintenance.
In my opinion, the queues and the AFK timer are currently well placed and balanced as it prevents players that aren't giving the proper attention towards the gameplay they are inducing for those that may produce an more watchfull gameplay time during said periods OR, otherwise, the cycle would keep on running until an fit player is picked.