I think I've settled on my strategy, as TCON upgrades were the only thing making me consider renewing DM (after the loss of usable SDC, the downgrading of the SkyClubs, the fine print on MQD, difficulty of redeeming award tickets, etc): I plan on dropping to GM (since SP and international lounge access are about the only two remaining benefits of status).

Effective March 1, my TCON flights will go to "best fit", which I suspect will mostly be B6. My non-TCON domestics will stay on DL (at least for now), and should be enough to get to Gold. My INTL will go to "best fit", which will typically be whatever carrier offers W on the route I need, or maybe DL where it makes sense (eg: JFK-DUB which is too short to matter, or perhaps a TPAC if I get the global certs as my "going away gift").

I don't have the interest to match to AA and sit through that merger. (And let's not forget that AA's international flagship is a 10-across-in-Y 773.)