My view: high performance comes with a price, and we should all contribute to the development of the guild.

This is why I have the following proposal: first, there should be an entry cost for new comers. This contribution should be set at a fair level, not to act as a blocking point for fresh members, and we should have one or two empty places at any time. These spaces can be created by kicking out the low-performers (in term of contribution). We can use the ranks to give some protection to colleagues that contributed a lot in the past, but have a period in which they are not very active anymore (for example, you need an overall contribution of 5k to be a senior member). This limit will be adjusted on weekly bases, pushing everybody to contribute more and more.

Only members of the lowest membership will risk to be removed (senior members will not be removed, as long as the keep above this limit).

Also, we can create a second guild for juniors (similar name, to act as a lower lodge). Top players from the junior's guild will be promoted to the major guild every month. We can use an alt-account to drive the junior guild - as probably everyone will like to promote at one point.