Yes and No, IMO.
If you get a targetted offer (DoC routinely posts when the "waves" come out), they don't contain the lifetime restrictions. Personally I've never received one (you input your skymiles #, name, and I think something else and it tells you if you're eligible or not). Gee, amazing that they actually check/enforce (unlike apparently Citi).

Theoretically (I shouldn't say this it's been proven it works) if you wait 7 years (maybe over 7) you can get another DL Amex card (that you don't currently have) and get another SUB since apparently "lifetime" in Amex-land means like 7 years. Like: 8 years ago you had the Delta Amex Gold and cancelled it back then. 7.whatever years later you re-apply for Delta Amex Gold and can get the SUB.

Now, is that wise, given the current state of affairs? IMO, probably not. I don't think DL would get you, but Amex might (and claw back the miles and shutdown your Amex accounts). Although it would seem even in that case, DL probably keeps your account open (albeit minus some miles maybe).