Multi-chip designs are limited to the upper tiers for this gen. Think, $500+.There's probably other shrinks elsewhere. Missing backwards compat for deprecated features like the old geo pipeline, more SIMD32 versus work dispatch, etc. Arch improvements so far seem more about fixing old problems like needing to decompress in certain stages; and the improved RT pipe that was patented a while ago used the texturing units, meaning any expansion there is probably minimal. Bridge is also pretty minimal afaik, could see the chip end up in the mid 300mm range.
With the price hike from TSMC and extra dies a single 128 simd32 compute chip alongside bus and etc. probably costs a bit more to produce than the 6700xt. Thus my guess of $500 for a full chip and $400 for a partially disabled/binned (non "xt") version. Of course if things go bad those prices could rise by $50-60 or so
Hopefully though it'll be a bit smaller, and that price increase won't happen. It'd be real nice to see 6800(non xt) or a bit better at $400.
Edit- really though I don't understand the rumored specs entirely. The most logical compute tile should be like, 96simds (48 RDNA2 compute units). The cost would be tiny, probably as low as a Navi 23 (6600) board for each compute die. You could pair it with 128bit/256bit/etc. bus and SRAM as you scale up to 1/2/3/4 compute dies. A single one would be theoretically 20% faster than a 6750xt at minimum, and more for raytracing. That should be the sweet spot for cost/performance right? Eg 12 teraflops/8gb for $329; 15tf/16gb $400; 24tf/16gb $700; 30tf/16gb $1000; 36 tf/12gb $1250; 44tf/24gb $1600; 58tf/16gb $2500.