first I'd like to indicate what you need to successfully accomplish the PoS attack you pointed to.

a) disable checkpoints and have users download your release.
b) procure many PoS accounts keys with very large stakes.
c) have powerful / quantum hardware to build a myriad of chains to get one with the cumulative difficulty higher than the valid chain to be accepted by other nodes.

Each of these is not trivial, combined they are the pigs can fly at supersonic speed kind of fantasy.

Now for the theoretical attack vectors on PoW, these are well known but I can't refuse since you asked.

1) voluntary collusion of miners.
2) involuntary - high vulnerability of centralized mining physical infrastructure and known locations to state level attacks.
3) dependence on ever increasing hash rate and difficulty, security is weakened if price goes down, dependence on energy infrastructure.
4) quantum computing.

You can dismiss these attack angles because they haven't yet been used. TPTB_need_war disagrees with you.