Lets asume d@ the moon eye plan is complete and the jutsu is cast, what do u think will happen during the day when the sun is shinning and the moon is not around?
The world would function a/c to the caster so it doesn't matter about sun and moon... The only thing that would change would be the negative attributes of this world...
Well I always assumed that Madara simply needed the moon to initially catch multiple people in his infinite Tsukuyomi. I can't remember it being explicitly stated that people had to consistently maintain eye contact (or the like) with the moon in order for them to remain trapped inside the illusion; that's to say, once they've been caught by the moon the first time, they won't need to be caught again - the genjutsu will be 'infinite'.
I doesn't require the moon to be there all the time...
Just like how if someone uses the Sharingan to cast Genjutsu on someone, they don't have to look in to their eyes constantly.
It's either an eternally lasting effect or it just keeps going because the moon goes past every day anyway.
Or maybe Obito just intends to make more moons with the Juubi's power...