It all depends on the difficulty. It's rather easy to project what the next difficulty jump will be, however it is much less accurate to predict where the difficulty will be in a few months, a year, etc.
Edit: if you want to mine for profit, I suggest a Scrypt GPU mining rig for starters. Cheap, you can resell the GPUs, and they are profitable. ASICs are much more unpredictable and have little-to-no resale value after they become obsolete.
Well. from what I see the best cards can pull out about 700 MH/s, which is not much comparing to the 30GB/s ASIC. + the difference in price between those two isnt that high as I would have expect it to be