March difficulty will most likely be in the 2.5b-5b range.
this is very unlikely as it requests the hashrate of 20 PH or more.
It's interesting to see how we used to think in November. Today in January bitcoinwisdom.com reports:
Bitcoin Difficulty: 1,789,546,951
Estimated Next Difficulty: 2,333,891,351 (+30.42%)
Adjust time: After 1232 Blocks, About 7.3 days
Hashrate(?): 15,657,784 GH/s