I'm actually a little disappointed that Martin intends to explain this. Sometimes keeping things like this mysterious make the story more interesting.
For some perhaps. The key for me - if it was going to be a science fiction explanation, the explanation needed to explain how the uneven seasons work. Unless the how then is central to one of the plots, then it doesn't really matter, and the uneven seasons are interesting background that would only need explaining if the audience required "proof" that it has a science fiction explanation.
However, with it being a magical or supernatural explanation, the how can be thrown out the window ("A Wizard Did It"), but then we get a much more interesting question of "why?" And, in my opinion, particularly in an epic series such as this, all why questions must be answered for a satisfactory ending.
I disagree because I see it as "Just the Way Things Are" and not "Crucial Plot Point."
I don't recall if it was a throwaway line or something from one of the So Spake Martin Q&As, but I'm pretty sure there was a mention of the seasons being normal far in the past and only being unpredictable more "recently", with recently still being described as centuries if not millennia.
Thus, it's not strictly a "just the way things are" because they haven't always been this way.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.