Gotta have some limit, 4x the current limit of 256 seems reasonableish. Dual socket Epyc 9654 is 96 cores * 2 threads / core * 2 sockets = 384 threads. Intel says their Xeon Platinum 8490H can live on an 8 socket board[1], if you can find one (SuperMicro has one, no price listed [2]; not sure if this is really an 8 socket system, or if it's 4x dual-socket nodes in one chassis?); 60 * 2 * 8 = 960, so that's within the limit, and 8 socket boards are pretty difficult to find.

[1] https://ark.intel.com/content/www/us/en/ark/products/231747/...

[2] https://www.supermicro.com/en/products/system/mp/6u/sys-681e...