Transfer to congested servers.

[Stillwaters]

This is hyperbolic nonsense. According to the most recent unofficial census Balmung has just shy of 22,000 active characters. Levi and Cactuar come second and third respectively at almost 17,000 each. The gap has closed tremendously. In fact, Gilgamesh isn't even top three in terms of active characters now. Both will unlock soon enough, though probably not before 2018.

Cactuar is fourth, behind Omega as well as Leviathan.

Difference is actual active population, not characters created. The census counts any character that has any change (achievements, mounts, level) count toward active players, but not ones that consistently play. Only Omega has closed due to active player numbers reaching the same as the other congested servers. One can assume that Cactuar has not reached the same amount of active players as Gilgamesh, despite having a higher population count.

[Bourne_Endeavor]

In the amount of time since Balmung was locked, only ~2k players have transfered off (Based off a 24k player peak I read prior), most likely those less attached to the server and willing to boogie. So what's left is the people who have dug their heels in. It's not totally baseless to say the server will be fubar until 6.0 unless the devs give people an incentive they can't refuse

But they can't even incentivize the subscription model so that won't ever be a thing either.

Not according to Lucky Bancho's census. Balmung had 29,000 active characters prior to Stormblood's launch and has dropped to 22,000. While that number has inevitably slowed, multiple servers are catching up. So I sincerely don't they keep Balmung closed for four years.

Cactuar is fourth, behind Omega as well as Leviathan.

Difference is actual active population, not characters created. The census counts any character that has any change (achievements, mounts, level) count toward active players, but not ones that consistently play. Only Omega has closed due to active player numbers reaching the same as the other congested servers. One can assume that Cactuar has not reached the same amount of active players as Gilgamesh, despite having a higher population count.

Which was Lucky Bancho's. His use mounts, minion and achievements to monitor character activity. Levi and Cactuar come head, with Omega only at 15,000. SE probably has different ways they evaluate this however, hence why Gilgamesh remains locked despite having lost a considerable amount of active characters.