This means that in 6 months time 10 Erupter for a total of 3330Mh/s will become useless, am I right?
That depends on if the diff-growth stays exponential (it will most likely for the next couple of months) and how the gradient of the diff-curve will behave - will it get even steeper (%raise/diffchange goes up) or more flat (%raise/diffchange goes down) and when.
Also really important is the development of the exchange rate for BTC. If it goes up to like 1000$/BTC in 6 months sure you can still make a little profit. If it stays the same you will have to pay at some point for electricity costs, if it falls, you loose money faster.
But if the exchange-rate rises to like 1000$/BTC in 6 months even more people will buy into ASIC mining because they think they can make a profit - this will increase the diff-rises furthermore..
No one can predict that.
Stick to your 10 erupters, play with them, have fun, support the network. In the winter it will be a "free miniature heater" (direct the warm air with a small and silent USB fan into your direction ) and after that you have to see..
Thank you for all the grate infos provided. I definitely needed some mining basic to start off with.
I dont really have any expectations at the moment apart from the hope to get my investment back, and like you said if in 6 months time price will go extraordinary up I will be making some money, otherwise I hope LTC will adopot ASIC afterwards.