It seems to me that their decision was made in a rush and considering the bad moves SE has done in the last few years, that wouldn't surprise me.

I, too, will continue paying even after the final update, I still have a lot of things to do and I would like to stay in Vana'diel until the end, whenever this may be.

I don't think XIV is as successful as they make it out to be and it probably has something to do with their decision regarding XI.
The thing is, and it has been said by others, XIV is a completely different game, a bad game according to me. Me and my friends played during 1.0 and then 2.0, we all came back running to XI after what they did with XIV.

XI might be seen as a niche game, but there are people still playing, people who simply cannot find this "something" Vana'diel has anywhere else, there are also many players who do not play anymore but are still deeply fond of this game, do they even realize this ?
What I don't understand is, if their decision wasn't made in a rush, why make all these QoL updates, why add RoE, why add job points, why even increase Mog Houses size in the update to come ? Why make so many useful changes and additions only to say "we will stop updating the game after November" ?

There is something off, disrespectful and illogical about what they plan to do with FFXI. And considering their games since FFXII, FFXI will probably be my last SE game ever. I tried XII, XIII, XIV, Type-0 and FFXV demo and they were bad. I used to be a huge FF fan but enough is enough. Add on top of that that they keep popping games and remakes left and right, I do not believe one second that they need FFXI devs somewhere else.

I even told myself "why keep paying for XI now ?", I gave them enough money, money that wasn't even used for XI, but that is probably exactly what they want us to do, leave the game. Since I am still enjoying XI I will stay and express my disagreement with their decision. This is naive, I know they don't care at all, but if we can push the end of Vana'diel further away because we love and enjoy this game, then we should do it altogether.