Since you put it that way, it is probably a convenient way to carry your entire wallet with different identities with you on a small device. I'll wait till it evolves a little further or the price drops some more. (I don't have a trezor, or any other hardware wallet for that matter.)

For regular world "credit rating" you would need to consolidate everything into one identity though. There's just no way around that. One social security number / tax identification number / social insurance number / driver's license number / passport number. If you're a normal average person who would go through a normal average life, you need to stick to one identity for your home, your credit, your car and any loans from a normal bank.

We do that already anyway. The rest, like you say, can have as many identities as you require, effectively making it like electronic cash, and you simply ignore any "points" or "miles" or whatever. If it's a new identity per new transaction.