IMO you are right on that, however this is a failure of all cryptocurrencies, not DASH exclusively. Cryptocurrencies rely on attacker economist rationale, including Monero, Bitcoin etc. "Honest miners", bloat attacks vs fees increase (Bytecoin attackers (?) on Monero), etc etc.
Actually, AlexGR, he isn't at all right. Mostly because he presents one attack vector, which is nearly impossible to acheive, as the only issue. The point isn't to get a majority control over all masternodes, but rather a 90%+ minimum for less than 1%
chance of deanonymizing a transaction.
It's not a matter of how much it costs to gain control over the MN network enough to either deanonymize a transaction or other malicious actions (such as double spends, etc...) It's a matter of ability, and there is no way any entity can do this without just about everyone selling off their Masternodes, and only to this malicious entity in a free market. You think that's going to happen?
The nature of the dis-incentive is of the type he originally described. In other words, a rival with tremendous amount of money can theoretically attack the system. We are counting that this is not "realistic" to happen.
But the same is true for all cryptocurrencies (PoW, PoS) and their entire operation.
The same is also true for all mixing-based anonymity systems, due to the possibility of sybil attacks.
What are Monero guys saying against Bytecoin? "Ohhh the preminers hold 80something % of the first coins which can be used to deanonymize the mixin of later users..."...
Now, of course, there are degrees of chance, probabilities, etc etc on what might happen. But, in the end of the day, even a 0.000000000000000001% chance that something might go wrong, is proof that the system is not designed to be 100% robust in itself, instead if operates with certain assumptions on the economical behavior of the users of the network.