I believe the Cisco event on 9/24 will clear up the FUD regarding their relationship wil EZchip.
Most likely, the new Cisco X1 chip is intended for the CRS "core" router product line. It would be a 3x improvement over the existing CRS3 NPU. The fastest speeds/feeds NPUs ALWAYS go in core routers first, since they handle the most traffic. Cisco has ALWAYS designed its own NPU for CRS products. AFAIK, EZchip has NEVER been in the CRS, and I doubt they ever expected to be.
Cisco has been laying off people in the routing area for years now. Given that NPU development takes at least 2 yrs, Cisco would have had to either a) fund a new edge NPU team 2+ yrs ago (in the midst of a huge 2011 layoff / reorg) or b) used the CRS NPU team (in which case where would the next CRS NPU come from) or c) developed a "hybrid" NPU that could be used in both CRS and ASR (which would involve some difficult engineering tradeoffs).
Given the high cost of in-house ASIC development, and Cisco's intense desire to control costs, IMO it is more likely that they will continue to leverage EZchip and/or other companies' NPUs rather than expand in-house development.
Cisco has bought design teams in the past, already has a presence in Israel, and is searching for good uses of its overseas cash. So an acquisition is possible. But I think it is unlikely, since they appear to be focusing most new investment outside routing/switching hardware.