If you really want to look at the long term, think of it this way. Eventually, an equilibrium will be reached between the people who can't maintain profitability and back out, or people discouraged with the btc values and back out, and those who stay in. Difficulty will level off, and eventually profitability will return with you at an advantage. This is in the long hall. Bitcoin has had one boom so far and I don't believe this is the end for it. I'm at about 1ghash/s and I'm satisfied to hold it out.
I totally agree with you. I keep on thinking this is over, and telling people on the forums not to bother building a new rig because there's no way they'll get their money back, but this BTC and NMC just will not give up. It just seems to keep on going and going.
The last week and a half was very nice, as I went to the NMC side, and was making a LOT of money per day (compared to BTC that is), but the good times ended with that, and we are now back to a more realistic level of income, on both NMC and BTC.
Today, again, I thought nuts to this, there's no way I'm making enough profit to warrant the hassle... I have to move the machines between rooms morning and night, but on running a test I found that my income was potentially $60 per day, with electricity @ $4 max per day, so definitely still worth mining

To the originator of this thread, you should just get down and mine with all that gear. You never know, you may do well.