It really depends on how much eAsic can further optimize the SHA-256 mining code to fit into their "eCell" architecture. The first estimates go for 16GH/s based on Ken's initial RTL code, but tbh I'm expecting even more upon further rounds of optimizations with several specialized engineers working on it full time.
Let's not forget that eAsic also does a design conversion to standard-cell chips (what they call their "easicopy" process) for even further performance/lower price; this is their design flow on that, notice how well it correlates with the nextreme design process, saving a lot of work.
Yes, they are that good. They grew 980% in 2012, let's see they break that in 2013.