Don't look to DL to see where this is heading. Look to AC and their Tango fares.

DL can't be "that" restrictive at the moment as they are the only major U.S. airline with these kind of fares. Now that AA and UA have signaled to DL that they will start with these fares you better believe they will become even
more restrictive.

The ONLY way we as passengers can stop this is to become a free agent and book whoever suits your schedule and price point regardless of alliance or partnership. As long as the airlines feel we are beholden to them for "status" then they'll keep eating away at the benefits.