Idea: Merit system

[Bacent]

I think the game will cease level at 100 because that's the standard for FF games (i would say 99, but FFXIV doesn't have a subjob system and usually capstone skills are awarded on the 50/60/70/80 levels, not to mention having a lvl99 cap would be awkward). That said, progression beyond level 100 would probably be something else, like mastery levels or some other form of progression.

Merits would be bad only because it's an illusion of choice. Skill trees are fine in offline games, but as many have pointed out, the merit system in XI was a failure. They're only now after 15 years trying to fix them in FFXI.
As a reminder, in FFXI every job had 5 categories of merits to choose from, ranging from new spells/job abilities to passive traits. Each of the 5 categories ranged from level 1-5, and you had 10 max upgrades. So you could merely unlock all 5 categories at level 2 of their potency, or max out 2 categories to level 5 and leave the other categories locked. Problem was, it was nearly always the case that the most optimal scenario was maxing out 2 categories, and by not doing so you were chastized or unwanted.

Max level in XV is 120. Max level in FFTA is 50. With XIV, since it's an MMO they could go well above 100 if they wanted to. As of right now the +10lvl/+135ilvl cap per expac thing seems to be doing well enough. They'd been trying to bring in newer systems, like with the, what I personally find god AWFUL, elvl stuff/deleveling/special actions in Eureka which the community was really split on (Personally think they forced way too much into one side area).

Skill trees though have always had an optimum way of getting stuff that would help you the most or so (Or the best way to level them up if you could unlock everything). There's always going to be 'the best way to do it' no matter how a skill tree is brought in, and everyone will be forced into the same cookie cutter paths, and I personally think they should stay out of MMOs as they're either volatile or boring.