We've discussed this several times.
You are correct, the GTO is GM's current "replacement" for the Camaro & Trans-Am.
There will not be a new GM car carrying the name "Camaro" any time soon. GM made an agreement with the UAW and the Canadian government that the Camaro & Trans-Am could only be built at GM's plant in Quebec until the year 2017. That plant was closed in 2002 and has now been torn down, so there will NOT be a Camaro or Trans-Am for many years.
GM was planning a new RWD platform that would spawn 4 new 2 door RWD cars, Monte-Carlo, GTO, Buick coupe and Buick vert. But this platform has been more or less cancilled for North America. GM N. America is still working on it for 4 door cars only. Holden has taken over the program for 2 door cars (next generation Monaro). Whether there will be a 2nd generation RWD Monaro based Australian GTO remains to be seen.
By the way, GM canciled the RWD 2 door program so they could focus their resources on getting out a new generation of SUVs sooner. GM seems to have perfect timing these days, putting all their eggs in the SUV market just when it is crashing due to high gas prices makes perfect sense.