Secure Guest Users' Org-Wide Defaults and Sharing Model - Salesforce Security Update

Does anyone know the impact of the Salesforce security update "Secure Guest Users' Org-Wide Defaults and Sharing Model" on Agreements sent from Salesforce? We have a Force.com Site with a guest user set up so that we can send large documents, and that guest user has read/write/delete access on Agreements. My understanding is that once the security update goes into effect on March 1, 2020, a guest user will have only READ access and not be able to create, edit, or delete agreements.

https://releasenotes.docs.salesforce.com/en-us/winter20/release-notes/rn_networks_guest_user_sharing_rule.htm

https://success.salesforce.com/_ui/core/chatter/topics/TopicPage?id=0TO3A0000001Jp3&ref=related