I think that there are many good points to your theory, and I would like to add onto it by putting emphasis on three things: the genjutsu of tsukuyomi, the power of the ten tails, and the most recent film for Naruto which was written via Kishimoto's notes.
Tsukuyomi as a jutsu is very powerful, and it is important to note that it was referred to specifically by name when referring to the plan, infinite tsukuyomi. There is relevance in the particulars, and for that we should think about what tsukuyomi as a jutsu actually does. Tsukuyomi is a genjutsu unlike any other in that it the user controls both the time and space within the technique (Itachi controlled the duration of how long he tortured both Sasuke and Kakashi.) The time outside of the technique has no relevance to the time within, one second having barely passed despite the perceived three days while under its effects.
Next I would like to briefly talk about the ten tails power. In a complete form the ten tails was known to have abilities and chakra that affected the entire world (moving continents, being the primordial base of chakra and human existence, etc,) it's incomplete form being capable of launching attacks that could hit continents away, in addition to causing localized natural disasters. Therefore we can assume that a controlled form of this raw power, as an actualized jinchuuriki is supposed to possess, has great potential. Enough chakra to cast and maintain a jutsu for potentially as long as one wishes.
The last point I will make includes the movie and should serve to wrap things up. The movie's premise was all based around an incomplete version of the infinite tsukuyomi, the "limited tsukuyomi." Forgive me for spoiling some of the movie, but within this movie both Naruto and Sakura were caught within the limited tsukuyomi, and spent around two or three days within the illusion. When they finally managed to break it, it was apparent that no time had passed in the real world, despite their experiences within the dream world, as in normal with a normal tsukuyomi. I believe that, rather than there being entirely separate dimensions, it may simply be that each individual is simply in their own illusion, with the necessary chakra for these many individual illusions being provided by the ten tail's chakra. And they will live out their lives, from whatever age they entered until whatever age they "want" to die, because as previously stated, time means nothing within the illusion. Obito himself can enter his illusion and live in it as he wants to look (Madara had previously demonstrated that one can alter their own appearance within the illusion when he first briefed Obito on the plan in their hideout) and despite knowing it was all an illusion, the fact that he could physically interact with anyone in it as if it were real is the appeal to him (if you are familiar with "The Matrix," Cypher's character is similar to Obito.)
This is what I thought, and I look forward to your opinions.
