It depends on when you started mining and what you paid for the miner, but most people that bought the USB miners will never make a profit in BTC. And even if they make a profit in $, it would have been more profitable if they just bought the BTC outright, instead of mining it.
It depends on how much the difficulty rises, but it is unlikely that any USB Erupter will ever mine 2 BTC or even 1 BTC. If the difficulty continues to rise at 20% per period for the next few months, then it is unlikely that miners starting today will ever mine even 0.5 BTC.
On the other hand, there is always a chance that the the difficulty will to fall below what it is now...