You can, however, charge it with a combined cable that uses copper to bring power to the laptop (and optical converter), and optics to transfer the data.

> But you can't charge a laptop with an optical cable.

I don't think that matters. If you care about full PCIe through a cable you presumably are charging through a different port.

> As for copper, I understand you don't get 40gbps with a 3m cable

Actually you do with TB: that's the spec and you can find independent verification via a web search.