My script is based on the one by Christof Jentzsch, and in my eyes a little bit more beautiful ;-)
But if you run the script, you'll be able to see that the diff from the block 200.000 until now... aren't equivalent (on the time) for the diff registrered here etherscan.io/charts/difficulty. Not even close. – Sirvaude Jun 5 at 8:01
That's true because the difficulty bomp is not the only factor that affects mining difficulty. And thus it's only a prediction, because there is always the unknown factor of actual mining hashrate on the network.
May 10 was the day I ran this script. I took the difficulty/hashrate values from the blockchain on that day. Block 200k is the block where the difficulty bomp activates on the network.
Also check out this thread with a quote from Vitalik Buterin which basicly states this script is not accurate anymore as the difficulty bomp was weakened in the Homestead release to give more time for Serenity.
TL;DR Blocktime will be annoying in second half of 2017 and the final doom happens somewhere in 2021. – 5chdn May 11 at 8:29