The amount of CPU power necessary to generate a PoS block is nominal at most. A single very old computer would be able to handle creating every single block of a PoS coin.
If it does not cost anything to produce a PoS coin then it does not cost anything to attack the network. As a result any PoS coin can be attacked for free
If it does not cost anything to produce a PoS coin then it does not cost anything to attack the network. As a result any PoS coin can be attacked for free
Blah blah blah, do it!
In the end the truth is bitcoin is consuming 10% of its market cap each year (500 million $) to mantain a decentralized (not so decentralized lately) ledger.
10% a year today, 6 % in 2016, 5% in 2017, 3% in 2019, and 0.5% in 2026.you can just buy all the NXT you can for the current extra cheap price, sit on them and enjoy all the benefits of a natural steady deflation which increases your purchasing power. 
That something I like about Nxt. Bitcoin is Disinflationary, while nxt has no inflation besides the ICO. This may be its undoing though because distribution wasn't the best initially. The nxt currency isn't deflationary in of itself .... are there any true deflationary currencies in existence? (I am not talking about deflationary in reference to minting vs adoption)The 10% will not decrease, as shown by the last halving. If it decreased to 0.5% in 2026, then it will only cost 0.5% to attack the Bitcoin network, which is laughable as security.
I think you can actually try an attack spending 2 or 3% of the bitcoin market cap.
When inflation drop to 0.5%, 0.1% of the bitcoin market cap will do the job, maybe even less then that if the mining has centralized further.
By then, not the government, not a terrorist organization, not an asteroid but speculation will have destroyed it.
And for those who think transaction fees will be enough to pay for the security i want to ask them how useful is bitcoin if you must spend 2 or 3 $ to do a transaction.
The bell shaped curve of yearly transaction revenues from fees, has a point of maximum which is not proportional to the market cap of the coin, if you raise fee beyond that point revenues will drop and the same will happen if you set minimum fee too low, i don't know how much total revenues from fees could be at best, but i'm sure it will not be enough and it is a very stupid idea imposing 100% of the costs on those who make transactions and will porbably result in a disaster.
Cost of security in a POW must be proportional to market cap, and must be paid by stakeholders via inflation like it's happening today.
That's why bitcoin economic model is actually working, neverending inflation is necessary for POW to continue working properly.