Zardnaar
Legend
I wouldn't. I would publish level 15-20 adventures that explicitly weren't "endgame" adventures. Honestly they should make one of their anthologies that is just high level adventures.
I Honestly think the "They don't sell" bit is self fulfilling prophecy BS.
It may have become self fulfilling but the sales numbers for some older product is out there.
The high selling stuff is basically core books, Basic boxes and Gary Gygax adventures and a few like B4 and X1. The made adventures for CM part of BECMI
Paizo said something similar. OGL has been around 25 years. 2E and 3E had products like High Level Campaigns, Netheril, Epic Level Handbook. Dungeon magazine had several adventures.
If there was massive demand for it someone would do it. Product was made.