From what I understand the genesis is not modifiable afterwards, but you're not completely lost if something needs to change, but what about:
-If I want to change gasprice to 0, I'm guessing this has to be in the genesis file, and there's no other way to change your mind.
-Disabling mining altogether for a private blockchain
-How to configure the blockchains private peers?
Once I start a blockchain, how useless is the data to other blockchains, should I want to migrate ever.
Apart from depending on which blockchain, is this even possible or doable: exporting contract/transaction history data.
Or alternatively, switching to another blockchain at a certain point, but still having the legacy blockchain involved somehow?
The last one seems pretty improbable, or at least a hell of a task.
Ethereum seems a good choice for what I want, but keeping the genesis in mind, and having to decide on a few key things, and never being able to change it, is a very interesting challenge. And I'm curious how others are deciding this.