Can ASICS in general, and specifically any of the models coming out soon merge-mine other cryptocurrencies?
Yes. The ASICs themselves only perform the SHA256 calculations, they do not deal with anything protocol related and as such can merged-mine exactly the same as existing GPU and FPGA implementations. In other words, merged mining is part of the protocol, ASICs just do the math.
The standard rules of merged mining still apply, of course. The alternate currency must also be based on the same type of SHA256-based proof of work as Bitcoin and has to have implemented merged mining in their own protocol.