I have an estimation, and it is UP.
The difficulty is based on the hardware people are ordering and putting into service. You would need to investigate the possible delivery dates of several different ASIC miner companies and the hash power that they will deliver. Since a lot of this is contract mining companies or vendors that keep their sales figures a secret, the best anyone can do is guess.
Newest miners are power efficient, the main factor is that they may never pay for themselves in Bitcoins.
And when making any kind of estimations about the difficulty because you want to calculate your mining profits or ROI, you also have to take into account the price of bitcoins, or at which rate you are planning to sell them.