I have accounts over 20 years old I use every few years. I would not be very amused if your suggestion takes off.

I can see simple things happening though that work towards this; for my pet project I just coded a feature that hashes email addresses of inactive (3 months without any interaction) and using another differently salted hash of their email address (which we then no longer have after this) to encrypt their data. They can still login, which restores their account and data without them noticing, but they will never receive email and possible breaches hurt less.