If the max supply of dash is let's say 25,000,000 (i can't remember the max at it is dependent on difficulty?) that means that the maximum amount of masternodes that could exist is 25,000 using my example cap. I'm pretty sure there are more bank locations than 25,000 world wide.
What happens when 1000 dash costs $1,000,000? Isn't that a problem when you have such a high barrier to entry? It doesn't sound like decentralization but quite the opposite.
It's like the barrier to entry of opening your own bank location (you have to have $X to do so).
If the collateral to run a masternode would be a "higher barrier", because of price, we could reduce the required collateral.
There should be no real disadvantage for the ones who already own a masternode, because they could split their 1000 vin into new masternodes and will get the same share from the block reward as before.
So we could scale to more "locations".
Ofc you could argue that Masternode owners would have to pay more for the network connection/location/traffic/...., but in that case the price of DASH should be assumed higher and so that is not really a problem, because the "return" would also be higher in that case.
Btw if i remember right Evan posted on this some time ago, and his idea was also to lower the collateral in that case of "problem".