Allow inline-editing of merge fields in Templates

This sounds like a different idea to me — let me see if I can get this straight. So say you have a “Mailing Address” merge field, that’s composed of the following fields:

{{MailingStreet}}
{{MailingCity}}, {{MailingState}} {{MailingPostalCode}}
{{MailingCountry}}

In Read Mode this looks like this:

123 Main St
Chattanooga, TN 37201
USA

But In Edit Mode you want this to appear as a single Textarea containing the contents that would appear in Read Mode? What would you want to do with this data? Save it off to a separate field?