I think they're saving as much RAM as possible for an M5 Ultra.

And I think they will drastically raise the price for 512GB Mac Studio M5 Ultra. I'm going to guess it'll come out to be around $13,000 instead of the $9500 for the M3 Ultra.

So it'll effectively cost $3k - $4k more for the RAM. Still might be worth it for some local LLM workload especially with the significantly faster prompt processing of the M5 series.