Considering Greek culture is foundational for Western culture, I think Greece into virtually any European civ makes perfect sense.
That would also apply to civs like America, Brazil, Colombia, Mexico, Canada, Australia, etc.
That's why the Rome>Spain>Mexico path seems like one of the most historical in the base-game. In this particular path, I wouldn't feel like I am actually changing the civilization I started with.
Sure, there are other future more potentially "direct" paths that could be introduced (Rome>Florence>Italy), but the game, specially in the future with DLCs, will allow for civilizations to continue after the Era change in a historically semi-accurate way.
Even if "Rome fell", its legacy continues on in many, many nations. In a sense, those "ancient" civilizations aren't dead, in real life/history, we are the continuation of those who lived before.
That reasoning made me reconcile myself with the idea of "civ switching" in Civ7.
As a Latin language professor I had back in university once said, rather informally: "Latin never went extinct, we (contemporary Colombian Spanish speakers) continue using it in one of its many modern forms"