This only relates to the production points on land of cards when they rotate out of modern. It doesn't really have anything to do with the Modern format beyond that. For instance, currently when Rebellion leaves Modern format, the idea is they'll have twice as much production points on land as they do right now.

If you want that to happen, vote no on the proposal and nothing changes.

If you do not want anything to change and just stay like it is in relation to the production points, then you'd vote yes and want this proposal to pass.