The intensity of mining (hashrate) has (virtually) no impact on the rate at which bitcoins are mined. BTC are currently mined at 25 BTC every 10 minutes, the reward halving every 4 years (next in 2016). I believe this runs until ~2140 AD.
This is not true. The network difficulty is reset every 2016 blocks so that if the hashrate that was being used the previous 2016 blocks continues to be used (and the same level of luck is realized) then the next 2016 blocks will take exactly two weeks to be mined.
Every time the difficulty rises, it means that the previous 2016 blocks took less time then 'expected' to be found.
It is really not possible to know with any kind of certainty when the last block with a block subsidy will be mined as this is largely dependent on the difficulty between now and then
Given your statements all agree with and elucidate what I said, I don't understand what I wrote that is "not true" - can you clarify?
The part that is not technically true is this:
The intensity of mining (hashrate) has (virtually) no impact on the rate at which bitcoins are mined.
exton was pointing out that the difficulty is based on the
average of the past 2016 blocks. This means that, as long as the has rate is increasing, when the difficulty adjusts, it doesn't adjust enough for the
current hash rate. As such the blocks continue to occur faster than an average of every 10 minutes. Furthermore, the difficulty adjustment doesn't attempt to predict how much more the hash rate will grow over the next 2016 blocks. As such, the blocks start out faster than an average of one every 10 minutes immediately after the adjustment, and then continue to occur even faster yet until the next adjustment.
Of course, this all assumes that the global hash rate will increase continuously for the next 125 years. It is far more likely that it will level off and perhaps even decrease at times (the most recent two difficult adjustments reduced the difficulty). Since it is impossible to predict how much or how quickly the hash rate will increase or decrease in the future, it is impossible to say if it will take exactly 125 more years, slightly more than 125 more years, or slightly less than 125 more years.
If it took exactly 4 years between block halvings, then the previous one would have been in January of 2013, and the next one would be in January of 2017.
However, since the hash rate has been increasing and the block have been coming faster throughout the past, the previous halving occurred in November of 2012 (almost 2 months early) and the next halving is currently estimated to occur in July 2016 (almost 5 months early). As such, it seems likely that the final block subsidy could occur as early as 2137 or as late as 2143.
