If U2F is not cross-compatible, then there is a strong argument to made to always have a second device as a back up stored somewhere secure in the event of loss or failure of your first device.
This is a very correct thought. And in fact, I was fighting back in 2015 to buy myself a spare Trezor. But for some reason i didn't. And he acted rather stupidly. Now I will have to wait another week and a half until the new Trezor is delivered to me. All these weeks and a half, I will not have access to either the mail or the stock exchange. In conditions when there is now a strong growth in bitcoin, it was rather stupid to be left without a spare Trezor. But apparently this will be a lesson for me for the future.