Oh, they said that they will:

We are going to roll this out slowly and carefully, with plenty of notice:

• While the policy takes effect today, it will not immediately impact users with an inactive account — the earliest we will begin deleting accounts is December 2023.
• We will take a phased approach, starting with accounts that were created and never used again.
• Before deleting an account, we will send multiple notifications over the months leading up to deletion, to both the account email address and the recovery email (if one has been provided).

Source: https://blog.google/technology/safety-security/updating-our-inactive-account-policies/