Thank you for the answer. I have delt with scaling DBs with tons of data so the alarm bells were ringing. DBs tend to be fine up to a point and then fall over as soon as the isn't enough ram to cache the data and mask issues of the DB architecture. With the exponential growth of both users and content to cache, my gut tells me this will become a problem quickly unless some excellent coding is done on the back end to truncate remote instance data quickly.
Sadly I am better at breaking systems in wonderful ways than building systems for use, so I can't be too helpful other than to voice concerns about issues I have ran into before.
It will likely depend on how popular Lemmy becomes as well as the server physical location \ DNS registry that of used.
Having a piracy channel on an instance located in a country that does not recognize intellectual property, and a DNS registration in a TLD that doesn't respond to piracy complaints should be pretty bullet proof. Only thing that companies could do at that point would be to try to get a court order to have the DNS entry blocked by US \ EU \ etc DNS providers, or a court order for ISPs blocking the server IP address. These could be easily circumvented by changing the server IP if it happens and updating the DNS.