About adding new instances to handle the load:

There’s four possible legal structures that could be behind a messaging service:

• political domain (state, city, …)
• corporate entity (typically for-profit)
• clubs (typically non-profit)
• individual humans

I think it fits the spirit of the Fediverse best to consider the lower two options. A club is a free get-together of humans for some purpose, such as sports club, literature club, you could have a Fediverse club. I highly support this approach, because it is non-profit-oriented, lives off donations, and is rooted by responsible individuals who do something good for the community. Also, individual humans can host smaller instances, but as the instances grow in size, having multiple people behind it to back it up could make things more stable over time.