You're really not enough providing enough explanation
For how your anti-99% attack system would operate.
It's not anti 99% attack, that simply shows you can't sell 99% of coins and then rewind if there's someone else. You still can force forks if you have >50%, but you can't force a fork if you sold them, because the buyer can also forge.
The whole point is that the cost of such attack is orders of magnitude higher than in PoW, as percent of market cap, especially in later stage, where there are only transaction fees.
Where do you get these 99% stake stuff?
PoS coins use 10% of stake and dropping as economic activity goes up. Let alone that their profits are tiny to justify such big stake in minting (Just early adopters minting to support their system). If a real economy exists many will put their coins in more productive uses than minting and will not even care.
Many exchanges or early adopters of PoS coins currently have stake history higher than current minting rate of PoS coins. Where is the security? This is a joke and not superior to PoW.
Why do you assume all these nodes will be online at the time of the attack?
Why do you assume that lending will be something everybody will do? Why do you assume that it will not backfire giving one person extreme stake history who might not care about the coin at the present?
Why do you say lend your coins to a person you can trust if you want to build a trustless system?
What about the fact that coins get lost and later stakers will have less cummulative total stake available?
Why do you assume that the rest honest stakers (those not having their coins reversed) will not mint both chains?
As gmaxwell said a rational miner will mine both chains to maximize profit.
All PoS coins are very centralized in their stake distribution and dont forget that when you say they are decentralized. Let alone all the other reasons PoS coins are not decentralized.