FFXI will only ever "end" if S-E goes bankrupt or is sold to another entity that phases it out of their business plan.
That said, if it does "end", I won't be starting any more MMO games.
I'll probably need to give up FFXI sometime in the next few years anyways. Once my kids reach school-age, I'm sure I'll want to be involved in their activities as a soccer coach, or baseball coach, or whatever they want to be involved in.