Nick, don't worry its not the way you express yourself in written form, its the errors in argumentation that throw people off so won't matter if you use a different language
"Today, more and more manufacturers are adopting the duel purpose and are succeeding beyond Porsche expectations." errrrrrr! (buzer sound) you specifically mentioned the Z06 and the GT-R that are moving in now... the C6&Z06 are not a 2+2, with worldwide service infrasctructure and as appropiate for all years round/climate use. And before the new GT-R there was.... long and behold... yes, the "old" GT-R Skyline which was essentially the same AWD four seater concept. I'm telling you, a big juicy steak will do wonders!

As to the GT2 dissapearing into the abyss when placed next to a F430, guess you haven't seen the GT2 "live", but given that thats not how you compare cars, if you compare them strickly for attention seeking value then yes, I'll give you taht, just like if you place the GT-R or Z06 you mentioned next to a GT2. But fortunartely, most of those Z06 and GT-R driven won't care since they will be having a hoot driving the cars instead of posing with them.
And the fact is that Porsche 911 sales keep getting more succesful year by year and Porsche has become the envy of the sportcar industry, something that wouldn't happen if they would be getting harder comeptition in real life, in fact its in the past were Porsche struggled more against the competition.
One thing though the new R8 (and future versions, V10 and spyder) specifically is the closest true competitor to the 911 I have seen in a long time, and a solid alternative... will be interegsting to see its impact in sportcar market the next two years, but I see other manufacturers that are standing to loose more than Porsche is.