So I've been bouncing between Final Fantasy XIII and XIV lately, and a thought occurs to me. I love the ability to change your character's class.
In Final Fantasy XIII, for those who don't know, you can change your characters from one "paradigm" to another. A paradigm is a preset class set for your characters. For example: Tri-Disaster has all three of your characters in their Ravanger roles. Relentless Assault has One Commando and Two Ravangers. The point of this allows you to alter your battle strategy mid-fight, in order to heal, rack up damage, debuff, etc.
The downside to this system is that you have to A) Preset your paradigms beforehand, B) Have a limited number of slots for paradigms (not that bad though, since it covers a wide spectrum of possibilities), and C) For a good chunk of the game, some classes are locked to certain characters, so say, character B can't be a commando.
All in all, it's a very interesting combat systems, and it keeps things interesting.
Onto Final Fantasy XIV, and how it contributes to this topic.
In Square Enix's latest MMORPG venture, you have a class that is determined by what type of weapon you are holding. Holding a spear? You're a lancer. Holding a sword? Gladiator. The benefits of this is that it allows you to change what you can bring to a group immediately, instead of running back to town and changing your class there. Actually, other, non Final Fantasy MMOs I've played lock you into your class at character creation, which is a huge bummer, and just forces you to have multiple characters, thus pay more, in order to see different playstyles. In addition to this fluid class system, you can also equip some skills from other classes you've leveled up. This means, you can have a Lancer who has Cure and Fire spells queued up to deal with monsters in your area. The trade off of this is that it might not always gel well, what with Lancer's not having amazing spellcasting stats. I'm willing to trade optimal synergy though for flexibility with my characters.
So, I kind of want to hybridize these systems with a few alterations. I want you to have set classes you can level to learn the abilities, but then, after you hit a certain level, or reach an arbitrary story point, you can create your own class. You could choose what stat bonuses you wanted for your class, so you can sort of spec your class to mimic main ones. So for example, if the default Black Mage class gives you a bonus to Magic Damage and Magic Resist, you could make your homebrew Mystic Knight gain a bonus to Magic Damage and Vitality.
to determine your abilities, you would either have a set number of resource points to spend on abilities, or limited slots, either or could work. Take some abilities from your Warrior class for an HP boost, ability from Thief class for increased Critical Hit Chance as passives, then take Thunder, Ice, and Fire from Black Mage, and then Guard, Provoke, and say, a special blade attack from Warrior to craft your custom class.
Do this for all your characters. And now you add the Paradigm system from Final Fantasy XIII, and you can now flow between preset classes, custom classes, and other things on the fly. This will allow the enemies to either be more difficult to compensate for increased player coverage, and you could even introduce new things like locking a character into a class as a status ailment.
This is just something I thought up. I know the programming and implementation for this would be tricky as all hell, but it's something i could see people sinking tons of time into tinkering their characters to match how they like to play.