I don't 100% agree with your assessment. All this email says is that the affected ticket holders are protected from any price changes/donation requirements for three years. It says nothing about reseating or reindexing for the general stadium population
As I read this, I thought the presence of donation color levels indicates the "reindexing" that will take place in 2025.
Those displaced from the former public sections (no donation required) will be able to pick from any of the vacated student sections with no donation required until 2025. At that time, people will have to donate at the appropriate level to keep those seats. Otherwise they will need to move to seats in a section that matches their donation level.
And although it doesn't say so on this chart, I think there is a limit of 4 tickets for each donation that will also be enforced in 2025. I suspect that there will continue to be no limit on number of tickets in the public/no donation sections.