Well in my opinion this is what SE should do.

2011 Additions

Patch 1.18 (June)
-Finish Remaking the battle system + Balancing of classes
-Adjust Behest and Guildleves to be equal in all regions + put a solution for the things players do like fail leves on purpose.
-Introduce the first set of unlockable jobs.
-Introduce the Materia system.
-Adjustments to existing maps like Black shroud
-Encampments

Patch 1.18b (July)
-Fix bugs
-More balancing
-Introduce new side quests
-New NMs
-Expansion of companies

Patch 1.19 (August)
-Introduce Chocobos
-Introduce Ishgard
-New Dungeons
-Expansion of materia system.

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~Start of monthly fee~
after patch 1.19 I hope all the work the developers have been working on would be ready, that way the game would be at a good state to start charging the monthly fee. and patches should be more bigger since they have to worry less about revamping the game.

Patch 1.20 (September)
-Addons to the whole game. (Leves,Behest,Dungeons,Materia,etc)
-Final set of planned jobs.
-First stage of missing Classes. (Musketeer + Arcanist)
-New endgame activity (Rank40+)
-Lots of new Monsters like tonberries
-Monster Encampments
-A lot of new Quests and Missions
-First rank increase (Rank 60)
-Expansion of companies & city-state tasks.
-Bugs,fixes,adjustments.

Patch 2.0 (December)
-Adjustments + Fixes
-Addition of Missing Classes (Shepherd,Mystic,Bard) (To balance out DOM with DOW)
-Addition to events
-New areas (Paglth'an + O'Ghomoro)
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2012 Additions
~Announcement of first expansion for the end of 2012~2013 that introduce us to the region of the Garlean empire. Plus PS3 release with it and maybe the new Wii or whatever its called.

Patch 2.1 (Feb)
-Adjustments + Fixes
-Addition of Missing Classes (Flayer,Enforcer,Samurai)
-Additions to the game
-New areas (Xelphatol + Gyr Abania)

Patch 2.2 (May)
-Adjustments + Fixes
-Additions to the game
-Airships
-New Activity
-New areas (Dravania + Sharlayan)

Patch 2.3(July)
-Adjustments + Fixes
-Conclusion of main story line of eorzea.
-New areas (Ala Mhigo)
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Then afterwards I expect low content till the release of the expansion around (NOV2012~May2013)