How can we ensure all constituencies remain represented as the foundation grows?

[joshtriplett]

A question came up as part of one of the foundation discussions, and I think it makes sense to document an answer in the FAQ:

How will the foundation ensure that all constituencies remain represented, while simultaneously ensuring that the foundation board remains a manageable size?

Notable constituencies include:

• Rust governance team members
• Rust community members, as individuals
• Businesses with an interest in Rust, including:
  • Large businesses with no upper bound on size or revenue
  • Small businesses (based on some threshold of size or revenue)

Some concrete things that came up in the discussion:

• If there is a sponsorship tier that guarantees a board seat, the cost of that tier doesn't change based on demand, and there's no upper bound on the number of sponsors at that tier, then the board size may quickly grow unmanageable.
• We could increase the costs for the top sponsorship tiers, perhaps triggered by the number of top-level sponsors reaching a certain threshold. There are various ways we could handle that, but let's leave implementation details aside.
• It should still be possible for small businesses to sponsor and collectively select representatives for board seats, without getting "priced out" by demand from large businesses.