There is something to be said about running International rules for GT cars. Though the variety from Speed World Challenge, to Super GT, to FIA GT, and what not is kind of fun I'd rather see GT1, GT2, GT3, and GT4 rules be taken in Internationally.
GT1 and GT2 would have the exact same rules in Super GT, ALMS, LMS, FIA GT, Int'l GT Open, FFSA GT etc. etc.
GT3 there would be various National cups as well as the Grand-Am GT class and Speed World Challenge GT and FIA GT3 Europe would act as "all-star" races for the best in their Nations.
GT4 could run in Europe as it is slated to and Grand-Am could adopt the same rules as GT4 for their GS category so cars can travel all around the world and have a place to race. Also would allow manufacturers like Porsche to produce cars from the factory that are able to compete across the board without having to force teams to pay for various series specific upgrades on, for example their Porsche 911 GT3 Cup car.
Admittedly that does have its down-sides, for instance the interest from teams like LG Motorsports and such in Speed World Challenge would probably dwindle because it would be harder for them to run their parts on their race cars, which to me is the biggest draw of SWCGT.
m.piedgros