Interesting. Wouldn't it be more apt to call them distributed apps then ? If not everyone in the network participates it's hardly decentralized. It's also not the case that anyone could start to participate or did I missunderstand that ?
Serious question btw....not trying to hate or anything (shame one has to point that out these days...people are getting really soft skinned in this space).
Each sidechain is discrete, therefore not coupled with the main network.
A total of 101 master nodes can be selected by the dapp's owner, as in public keys are added to the dapp, allowing them to forge blocks on the sidechain.
In the future, this is something we will obviously address. What we have now is a starting point, therefore we will move further away from the model Crypti established as time progresses.
For example, we could implement the same voting mechanism used within the parent network, or maybe the ability to "bid" for a slot on a particular sidechain, we are open to ideas.