Actually, a higher rate of new devices also means the retail price drops. Providers like to tell you the device is 600 bucks but you're getting it for free with their subsidies, when really it's already a lot cheaper online. I got my Galaxy S II two months ago for less than half the initial cost, 10 months after it was released. Apple products on the other hand... They're always expensive.
While GS2 is great phone many US versions lack next gen features like NFC. Also display for all versions of GS2 is HDPI . With Galaxy Nexus and HTC One x XHDPI (Extra high Density) displays are gaining traction.Therefore GS3 is coming a right moment. Get all the great features of phones launched in last 1 year (which is a big duration in android world) plus set new benchmarks for future phones.
In the European tech press there's also a fair amount of rumble and hype about the next version. The Galaxy S II sold a fair number of devices (at the expense of HTC which didn't have a matching killer device), so we'll have to see.