I haven't seen the docs for it yet, but I can explain how I hope it will work. If you already have a coldcard and have it backed up in a manor you're happy with from a security standpoint, this allows you to type notes into the Coldcard Q, and export them in an encrypted format that can be decrypted on any Coldcard Q that is running the same seedwoods/passphrase. Some perks of this would be 

• Make a separate passphrase just for the following purpose. Leave some notes that would only be recovered if you passed away (a dead man's switch of sorts). Break the seed phrase into pieces with SeedXOR and give the pieces to friends/family. Leave them instructions on how to use a coldcard to recover a seed if/when you were to pass away. Then the M of N of them could combine their pieces, and read all the notes you've left to them. Instructions for how to get into your different accounts. Passwords for various things. Any other information you want passed along. The thought being, if you were alive, it would be unlikely M of your friends and family would collude against you (without you getting wind of it) to decrypt your post-death message to them. 

The encrypted exported notes are not a security risk, so you can store them anywhere. That way wherever you are; you could always buy a fresh coldcard, recover your seedwords, and decrypt your secrets on an offline device. 

You get redundant storage of secrets without them ever existing in plain text form on an internet connected device.

I should add, I'm aware seedXOR is M of M and not M of N. But if you print out multiple copies of each seed, you can pseudo create a M of N scenario, or something similar (with redundancy, or even giving some family members heavier weights).