If you consider the sheer number of ASICs reportedly in queue the difficulty rise will be large enough to diminish returns to the point of never achieving return on investment. Say you currently mine 25GH which is about 1/1000th of the total. That probably costs about 20K in GPUs and boards.
Now to have 1/1000th of the hash after ASIC stabilizes you would probably need to spend well over $20k.
Unless you got in very early on the ASIC batches you're probably screwed as people will keep tossing money at it in hopes of getting rich.
I think the only ones who will see guaranteed profits from ASIC are the manufacturers (like a gun dealer arming both sides).
This is the sort of thing I'm worried about. But don't miners make a profit mining with their GPU rigs now? Why wouldn't ASIC rigs make money once all of this levels out? When the difficulty goes up, wont the value of BTC change to reflect that?