I cannot see this ending well for alternates. HitBTC and Poloniex are so deep into Monero, where unless they start covering their ass now, then we're looking at international raids and confiscation of coins like the Silkroad. It will be a very red week and many alternates would see 5%-10% of their total supply confiscated as evidence (and presumably later sold at some auction). There is a remote possibility, much like Bitcoin right after Silkroad, that the liquidity being seized could result in skyrocketing prices.
Confiscating privacy coins would probably not net much information or evidence for the regulators. But you make a good point. Polo is a single point of failure. Hint Hint...Bitsquare.io