I havent played in this space for a year or three, but isnt this basically what everyone is doing for fixed port boxes? The os and routing daemons run on a set of low power xeons with a "bunch" of ram (RIB). That pushes forwarding down to the tomahawk et al asic (FIB). Unknown flows are punted up to the os, and possibly a remote controller (SDN). I thought this was already given inside the DC fabric, and becoming established for interconnect.

The places for the traditional giant carrier boxes are, and probably will be, wonky interface/proto/feature support beyond eth & routed IP.