Medallion marketplace conversions are now 6,500 miles for $50 guft cards for non-Delta Amex holders and 5,000 miles/$50 gift card for Delta Amex cardholders.

I think liquidating miles for gift cards is a waste, but if you don't need them for travel, then go for it. FYI Delta doesn't have last minute ticketing fees, so last minute redemptions can be of great value (DL and Air France are known to open up a ton of award seats as departure gets closer).