Here is my argument for going to full POS:
No more worries about pools dumping.
We can control the inflation and cap the max number of coins to a more sustainable number. (Look at BlackCoin, their only selling point was that they had POS and low inflation and their current market cap is over 2 million).
We don't have to worry about a 51% attack no matter what our marketcap is (as opposed to auroracoin which just died because of one)
Without being diluted by constant high inflation, we can focus on the fundamentals of the coin: which is that we have a great IP and branding that would allow us to compete well with established coins. Right now, the fact remains that we are not even 20% through the total number of planned coins, which is severely deflating current values. Allowing investors to not have to worry about so many more coins being produced and instead showcasing our strengths, would encourage invesment.
More incentive to buy the coin: Only way to get more coin is to buy it or hold existing coin.
where comes the mining part in this?
is it still needed for the chain to work?
if there is no more reward for mining then it is not needed to change algo right?
We need to change the algo to POS. That way the network will give rewards to those that prove stake instead of prove work. There is no traditional mining in pure POS, but can think of anyone with a wallet as a "miner" with a hash rate equal to the number of coins they have.