I don't think I've ever seen a timeskip be a good idea. Ever.

Now progression of time over the expansion? That's not a horrible idea. Even if it's not explicitly stated but just hinted at.

Also real talk but most of DT main was essentially this anyway, with most of the Scions taking bit roles. That said, an expansion where they shift focus on one or two Scions, having fewer of them for most of the story but getting into their motives and feelings and fleshing those out properly could get somewhere. Kinda like what Heavensward did.