Yep. You patch together early warning from a lot of different assets (carrier AEW is one piece of the puzzle)... picket ships/screen, patrol planes and surveillance planes, drones, satellites, stopgap solutions like what Chuck mentioned- all of the above with your own stuff and the stuff the partner countries bring.
I don't think the ESG concept, at least in writing and in formal doctrine, got much higher than a tacmemo. Neat jack-of-all-trades (almost all trades) task group concept, but it sorta fizzled out about ten years ago because we obviously didn't have enough smallboys to go around for it- not with all the other commitments (CVBG/CSG, BMD, independent ops/show the flag to friendly countries). I guess it's good that we keep on cranking out new Burkes since we're not getting any new cruisers, and the little crappy ships will be able to cover the friendly country/show the flag port calls that the frigates used to do.