Every few weeks, someone involved in Bitcoin writes the following somewhat breathless blog post:

1-Block rewards account for almost all mining rewards

2-Block rewards are going to drop (next drop in 2016/2017) and drop by 50% every four years forever

3-There won't be enough rewards for miners leading to insufficient hashing power

4-Therefore either (a) Bitcoin is in trouble (anti-Bitcoin camp) or (b) block rewards / inflation   will have to be increased to keep miners incented (pro-Bitcoin camp)


Points 1 and 2 are true.  Points 3 and 4 are an exercise in ignoring all data that you can't model, like the old cliche of the drunk looking for his keys under the lamppost because that is the only place he can see...

First, let's recall how rewards in $ terms to miners are calculated because that is what matters for hashing rate since silicon and electricity are priced in $, not BTC.

[# of bitcoins in the block rewards] x [price/bitcoin] + [# of transactions] x [fees per transaction]

Things to ask the author when you read the inevitable Concerned-About-Hashing-Rate-In-The-Future-But-Sanguine-About-Hashing-Rate-In-The-Present Blog Post.

What is your assumption for BTC price at the time of the block reward drop?  Also, in the long-future (2020s before it drops again!), what are your assumptions about transaction volume and fees?

As a general rule, nobody has any defensible assumptions because if you can predict the BTC price in 2017 and 2021 (note, you can't), you would have more lucrative pastimes than predicting hash rates!

I will declare upfront that I have no idea what BTC price will be 1/5/9/13 years from now (same goes for transaction volume) and I have never read any credible analysis suggesting anyone else has a clue either.
    

http://ledracapital.com/blog/2015/8/9/bitcoin-series-35