When we can expect block halving with currently network strength?
Each minute one block is generated, whatever rate nethash and the diff is.
We are now at Block 38,900 an blockhalving starts with Block 50,000
Use a calculator and you will see when we are aprox near the Block 50,000
Each Day 24x60 Block is 1440 Blocks. 50,000 - 38,900 = 11,100
11,100 / 1440 = 7.7 days
So on 2014-03-22 we will reach block halving.
Minimun one miner must keep mining to reach the target.
If the last miner stops mining before, we won´t reach Block 50,000