[gandhium]

My main concern about that - I'm not 100% sure that Google will not discontinue that in couple of years.

And for example: recently they've announced that 'Save to Google' extension will be discontinued in nearest weeks, without easy ways to exporting saved stuff.

[dudus]

Not sure how this new Google Titan key works but Yubico doesn't rely on anything other than sites that support it. If Yubico goes under tomorrow my key will continue to work for probably many years.

It's different than buying a device that needs update or server side controls.

This argument doesn't really matter here.