Etherereum Constantinople reward reduction

You are probably wondering what happens on January 16th. Well, here is what to expect:

Constantinople update will bring reward reduction and some more changes

Constantinople is coming!

• What will Transaction/confirmation time be?
  • Block time is now ~15 secs. For Proof of Work to do it's job normally, going to less than 15 seconds will create a lot of Uncle blocks, which are cheaper. That is because POW adds some more latency to the block time. This could decrease the reward. For Proof of Stake (when it comes) it might be quicker. Learn more about ETH uncle blocks.
• Is the block reward reduced after January 16th?

      Yes, reward goes from 3 ETH per block to 2 ETH per block. That is 33% less mining profit for the same power consumption - if the price remains the same. If the block time is also decreased (not by much). This can soften the effect which miners will feel as block will cost only 2 ETH, but should come faster.

• Will the Cost of transaction change?
  • Cost depends on how many transactions there are right now. Constantinople's EIP's are aiming to optimize smart contract interactions, so we should see a decrease in smart contract transaction cost (untill the next Cryptokitties dapp shows up to overload the network and send the price per transaction through the roof).
• Will the number of transactions/second change?
  • No. There will be the same average Tx per second. However EIP-1024 should optimize state channels (a type of side chains) which can cause a small speed increase.
• Will Constantinople bring PoS in Ethereum?
  • No, It's too early. EIP-1234 exists to reduce the block reward so it can cause a delay in the incoming difficulty bomb. It is now delayed for a year. At some point there will be a beacon chain and sharding chains
• Is this going to be a Hard fork or a Soft fork?
• A hard fork. This means there will be a brand new Ethereum blockchain which has all the new upgrades. All current smart contracts on the current chain will be copied on the new chain. 
• The "old" pre-fork ETH will probably have some value initially, but since no development is planned, it should die out.

Here are some more sources of detailed information regarding the upcoming Ethereum Constantinople update:

• Short video which describes the EIP updates 
• EIP number 5: EIP-1283.
• Constantinople progress tracker. (Very technical).