I was in a similar situation. With respect to choice benefits mentioned by MSPeconomist, SkyClub membership and hard-to-redeem global upgrade certificates are useful until January 31, 2026, which seems like quite a good thing.

On the other hand, with Diamond status in hand it feels like the MQD earned go to waste, since they will not contribute to future status.

Two special considerations for me. As a million miler, Diamond status moved me from top of the platinums on upgrade lists (e.g., position 6 or 7, out of the running) to more or less top of the upgrade list, with immediate consequences for upgrade success. Also, my frequent flying days are winding down; it feels like enjoying the next year and a half as Diamond on all of my remaining flights is a nice way to head off into the sun set, more so than what are really only a couple of trips that a conversion to RDM would have provided.