You are wrong in the Nehalem's case. Nehalem is using a bit modified and improved Penryn cores and replaces the old FSB with fast point to point interconnect.There is IMC also,but the uncore part is the major change.COre part of the Nehalem design is relying mostly on Penryn's strong(IPC wise) cores and improves them with one big addition called SMT. All in all an evolution in core part with mini-revolution in I/O and memory subsystem. Similar goes for K7->K10.5.
Bulldozer won't have the same underlying Kx architecture and will be design around totally different concept(in order to achieve maximum throughput both in int and fp workloads).The only thing that may resemble the Kx will be HyperTransport in the uncore part of the chip and FP/SSE in the core part.The latter(SSE units) will in reality still be 2x + faster than in the K10.5 due to AVX 256bit support and possibly other improvements.
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