Warmgun, unfortunately your theory is in contradiction to the game itself. You said that one can never see a timeline that has been destroyed due to time travel taking place in your future. If that is the case, Crono himself could have never seen the ruined future because time traveling in his future (both personal and objective) led to the events that resulted in it being destroyed.
As an extension of BROJ's comments, if Crono first travels at Time Error 3:56pm, then a James at Time Error 3:55pm will always see the ruined future, regardless of if James is 23 years old or 40. Curiously, this means that a 23 year old James could see the saved future and a 40 year old James could see the ruined future, depending on the Time Error. But not both in the same reality (for reasons Chrono'99 pointed out).
Side note: It is kind of disorienting having two Gurus of Time posting in one thread. I keep thinking your Faust.
Does Future Magus' quote that "there are as many worlds as there are potentialities" have any bearing on this understanding? Seems to me that Kato is positiing infinite dimensions, a Multiverse.
I suppose that depends on the nature of the dimensions. We can imagine two types of alternate dimensions. Let me label these Branching and Non-Branching dimensions, for ease of explanation.
Several Non-Branching dimensions could exist utterly separate from each other. Imagine our universe the moment the big bang occurred; everything that follows should be exactly known, based on the positions of the various particles and laws of physics. But it is possible for those laws of physics to have been different. There is no inherent reason, for example, that pi has to = 3.14. There could be an alternate dimension out there in which pi = 3.15, or even 3 flat. There would still be a multiverse, there would still be as many worlds at there are potentialities, but they wouldn't connect with each other like Home and Another world connect.
This is essentially the multiverse postulated by Arthur C. Clarke in his book,
Rama Revealed. There might be endless universes, but none of them can be traced back to another one.
A Branching dimension is more along the lines of what we normally mean by multiverse. A being takes an action and a universe splits off from that point, forming another dimension. And another will eventually form from that, and another from that, and so on. All the known dimensions could in theory be traced back to a single universe.
I think Kato has essentially set things up so that Chrono Cross is an instance of a Branching dimension in a Non-Branching Reality. The Dragonian Dimension, by random chance, happens to be very similar to the Keystone Dimension, but at no point in history did it branch off from the Keystone dimension. Indeed, that would explain why it is the dragonian dimension; the effects of gravity might be a little more or a little less powerful, sending Lavos flying by the planet rather than crashing into it. Similarly, Radical Dreamer is a totally separate dimension whose outcomes were similar but unrelated to the Keystone Dimension. Another World, however, that's a pain. A dimension split which doesn't happen in the reality. Thus the brouhaha over the fact.