I would love to carry around a bespoke talisman with some good heft that I sign transactions and messages with, when that becomes common. Reprogrammable or replaceable chip, and it becomes an heirloom pretty easily.

I think about how very serious transactions may happen between rich folk or families, and if "signing ceremonies" will become a think. With all the pomp and circumstance of a Japanese tea ceremony, but to transfer Bitcoin in full view of all involved. You'd need way fancier signers in such a situation than plastic coldcards.