Well FFXI started at 50 then was raised to 75 gradually through quests with the addition of the american/ps2 handling (or something close to that, it was back in 2002ish so even my memory is hazy) but then 75 lasted for a good 8 years of horizontal addition.

If they're going to raise it I'd assume they've probably thought most of that through. I think XIs level cap raise from 75-99 was a last hurrah of excitement hoping for it to stay alive, and with people disliking XIV, XI did survive and we're only seeing part of what their plans are.

Personally I'm hoping for more classes in the armory system for more customization, but they've been talking about "job" revamps so /shrug, no idea where that is going.

EDIT: Looked too much like block text so I spaced the paragraphs.