[e2e] TCP improved closing strategies?

[William Allen Simpson]

With the advent of more widespread DNSsec deployment, more UDP sessions
are likely to fallover into TCP sessions.

I've been informed that even today, with a more limited TCP activity,
busy servers cannot wait 2MSL to finish closing.

Also, busy caching servers run out of port numbers, and cycle quickly.
So there's ample opportunity for seemingly duplicate transmissions.

I've been searching my personal copy of the e2e-interest archives back to
'98 (the previous years are only on backup somewhere), and haven't found
anything on improved closing strategies.  Ideas?

Of course, there's T/TCP, but wasn't closing one of its Achilles heels?