Other PoS coins are going to be targeted soon and with an end goal in attacking NxT eventually.
Luke-Jr ultimately proved that PoW is flawed by successfully killing few PoW coins.
PS: Others can use the same tricks as you.
Agreed. Weaker PoW coins are vulnerable too. PoW is far from perfect but because of Bitcoins total hashrate it is far more secure than other coins.
I have been advocating adding a TaPoS layer in addition to PoW to bitcoin to further strengthen it, so I'm certainly not a PoW ideologue.