That’s a great question that should be asked and discussed more! Personally I believe that Shamir backup has qualities that are quite useful for inheritance planning. I have actually written an article on how to approach inheritance with Shamir backups: https://bitcoinmagazine.com/technical/protecting-bitcoin-shamir-backup. I think the crucial thing is to have some sort of “treasure map” that will become accessible to the family in the case something happens to you. Such treasure map would explain the nature of the inheritance and the location of the Shamir shares (not necessarily precise addresses to prevent theft if an “evil maid” discovers it). The precise inheritance plan is an individual thing, but I think there are some basic recommendations everyone should follow, as I describe in the linked article.

As for Trezor’s plans around this topic: we’d like to inform our users more about the use cases for Shamir backups such as this one.