Okay, let's forget about limiting the number of members a guild can have for now. But let's say we keep the idea of having a power limit. Instead of simply penalizing the guild for exceeding the limit, how about we reward those that stay at or below the limit. For instance, let's say that every guild that maintains a proper power level receives a bonus of exp and/or cash for each attack. This can also be augmented by the number of guilds that stay below the power threshold. 

For example, I am in a guild that has a power level of 45,000 (using a 50,000 PL limit) for each attack I do I get a bonus of 25% exp and credits (the amount gained can be a purchasable upgrade), there are 6 guilds in total that are below the threshold so for each of these guilds (not including my own) I would get an additional 5% bonus, making my final bonus +50% exp and credits. 

Any guild that exceeds the threshold would lose a % of the bonus based on how much higher their PL is than the threshold. If a guild is at 60k power then they would lose 10% of the final bonus. The power threshold can be increased as the guild levels allowing the guild to continue getting stronger. 

Another bonus that could be used involves guild territories. Perhaps in order for this feature to be used there would have to be x number of guilds within their power threshold. Let's say we continue using the 50k limit. Guild Territory Wars would only open if there are at least 5 different guilds at or around their 50k limit. There could be a range here so that mostly inactive guilds won't be added. So you would need 5 guilds with power levels ranging between 25k and 50k+. If too many strong people flock to the same 2 or 3 strong guilds then no one will be able to participate in the GTW. 

I realize this is all subject to whatever changes CK and GF make to the leveling system and everything, but hopefully at the very least this can encourage discussion and we can come up with even better ideas.