Hi Whitney,
Deactivating a marketing list has no effect on the records included in it, they will remain active. A marketing list is just a particular grouping of lead/contact records, so deactivating a list just means that you lose functionality for that group. For example, you won't be able to attach that list to an Email Send, but if you use another list with the same contacts, they will still get the email. You may want to add a custom field to your lead/contact records that your dynamic list can query for to get the right group assembled.