If it doesnt fall through, its gonna confuse the hell out of most people who dont follow this very closely. Why would google.com use .google etc? It weakens the brand of the original site. They might reg it and forward the whole lot on to the proper site, as per google.mobi.
I think custums are dead road as mostly surfers can't remember mor then 2-3 TLDs. If they go to honkywonky.org, later they will come back to honkywonky.com or .net mostly