I randomly thought about this, and I searched for older topics and I found none but one or two which were really, really old and I'm scared of reviving new threads, so...
My suggestion is guild gates.
As in, when you make a guild you can have a personal gate for your guild to use. It might be a buyable upgrade for your guild, or it might just come with the guild hall.
Anyway, the gate would basically be a place where just your guildmates could go, nobody else, and you would be able to customize it and build specialized gates, like maybe a special just about beast only gate so that you can go in with a piercing weapon and dominate everything, or something along those lines. The gate would function like an Arcade gate, but you wouldn't get paid for depositing minerals into it and there would only be ONE.
By doing that, it means that whenever your guild gate is in the building mode, as in you're depositing minerals to try and build it, you would have to go to an Arcade gate to be able to play, and if you want money for your minerals as a newer player, you have to go to the arcade. That means that the arcade gates won't suffer too much of a loss of players, because half the time people in guilds have to go to an arcade gate.
It would be a good addition to the guild hall, which is looking a bit empty, and a kind of goal, to collect certain minerals from arcade gates to develop a certain gate for... Whatever.
TL;DR: A guild gate for only guildmates which you can construct on your own to make specific gates with your guildmates.
I have to vote No to this, even as much as I want more things in the Guild hall. This would make farming super-easy to have our own private stratums that we can gear 100% against.