While the possible alternatives to an STI right now are pretty bleak, by this time next year there should be several cars on sale in the U.S. with similar performance, and in the same price range. I'll post the options I can think of off the top of my head below, along with a rough guess of the HP and price.
Mitusbishi Lancer EVO VII (AWD, turbo 4, 260 HP, $28K)
Infinity G35 (RWD, V6, 260 HP, $28K)
Mazda RX-8 (RWD, Twin Rotor, 240 HP, $27K)
Nissan 350-Z (RWD, V6, 280 HP, $27K)
Imprezza WRX (AWD, turbo 4, 220HP, 25K)
These are all cars I have my eye on currently as a replacement for my wife's 96 Eclipse Spyder GS-T. As long as Subaru can get the STI here by next year and price it around $30K, that's almost certainly what we'll get. If they can't, then we'd have to drive the others to make a final determination, but I'm sure we'd be satisfied with any of the alternatives mentioned.
I'd be interested to hear if any one else out there is looking at these or any other cars as alternatives to the STI just in case it comes a little later than expected.