VM stopped issuing email addresses to new customers in 2022, I think, and existing customers cannot create new mailboxes.
Opening a broadband account to save an 'at risk' mailbox has been suggested on here in the past but I cannot recall anyone doing so successfully. Even if you did that, trying to recover/re-associate the mailbox to the new broadband service would be subject to the randomness of outcomes that happen when dealing with VM as it would be a non-standard process. You may take out a new broadband service only to find VM can't / won't save your mailbox.
In any event, the general view of regulars on here is that there is no long-term future for VM email. All of VM's efforts of late have been aimed at winding down the service and minimising the number of email users. The only logical outcome is that eventually VM will pull the plug on the service or transfer it to a third party provider maybe to get rid of it.
The deletion process which normally seems to happen (which I experienced when I left VM) is that the mailbox enters a 'locked' condition to begin with (where the user cannot access it but it still appears to accept mail in with no bounce messages to senders). After that the mailbox is deleted and senders receive a non-deliverable message as the mailbox no longer exists.
In terms of effort vs reward, IMHO you would do best to notify people that the previous mailbox is gone and set up a new mailbox with a proper email provider (one which actually has the capability to run a reliable email service).