First thoughts...
This is a cop out because you don't want to expend the effort to fix a couple of the existing problems in GvG and add maps for eras beyond FE. And that is a shame, because it used to be practically unplayable and you got it over that major hurdle. But, while you were doing that, you removed some things that kept it hopping. One of those things is when you removed the nightly damage against sectors against most rocks and water. That helped to discourage a guild from owning half the map in multiple eras, because they had to maintain racks for that era just so they could replenish their damaged defensive troops. Another thing is when you were trying to solve the problem of a guild member trying to harm a guild by releasing a ton of sectors and instated the 4 sectors/player constraint. It would be better if, among other things, you let the founder decide that limitation individually for each member of their guild. And since founders can delete the entire guild, it only makes sense that founders should be able to drop as many sectors in GvG per day as they want to. This helps small guilds the most. Because they don't have the numbers to drop sectors as do large guilds.
For those of us who play this game for GvG, having maps beyond FE is a HUGE deal. I have stayed in FE for YEARS, solely because it is the last era where the goods deposited in the Treasury by my Arc can be used to play GvG. I have played this game for a long time. Before great buildings and before GvG existed. GvG is where camaraderie is formed. Many of us who partake in this aspect of the game, meet with our guildmates in voice chat to plan the night's fight and while fighting. We enjoy the strategy and tactics needed to be successful. This is not at all the same as GE. Which by the way is boring. I do it, but it's like a chore I have to do. Not because I enjoy it. Keep in mind that people who play this game because of GvG, invest money in this game for event buildings that give them higher attack/defense and would cease doing so if Inno's goal is to turn this game into a glorified version of Sim City or FarmVille. GvG is what made it stand out from the rest. Please don't look over that fact.
It was also suggested once by someone else, but I guess it didn't get the required number of votes to be passed on. That suggestion was to clear the GvG maps every so often. Maybe every 6 mos. Of course, some of the large established guilds who hold a ton of sectors aren't going to like that, but since GvG is supposed to be war zone, it would increase the action and give small guilds, or just newer guilds, a better chance to get involved.
Finally, here is an idea for another GB that would benefit GvG players. Offer one where we are allowed to change the era for which our Arc generates goods. The new GB would have a dial that would allow us to say, for example, this next period, produce Modern goods and put them in the guild Treasury. For example, since I am in FE, instead of my Arc depositing FE goods in the Treasury each time I collect it, I could, through the proposed new GB, tell it to instead deposit Modern. This new GB could also apply to the other goods producing GBs in the city if desired. For example, St. Marks, Rainforest, Lighthouse, RAH... Obviously, the only goods that could be generated would be from your current era and below.
In summary, please reconsider further nerfing this wonderful game by continuing to attempt to phase out GvG. Instead, spend the time to make it better and available to more players. People enjoying the game and on it more hours per day, tend to spend more money on it. Software companies typically, instead of fixing a problem in their code, just add more bells & whistles, which basically adds 0 to the usefulness beyond what salesmen could use to snow people with. Be different. Fix the problems. Create more maps. It doesn't have to be perfect; just better. You have a very loyal following by some; it's up to you whether you drive us away.
Thank you.
Note: I also recommend you start including a panel of hard-core GvG players on your advisory board that you run by any proposed changes. These people, chosen well, should be able to see the ramifications of something you are thinking of doing and advising you of such, so that you could make a better choice if needed. Only real players know this. Not people who know how to code what happens when you press a button, but little about actual game play. Nor brand-new players who don't yet know the game and who aren't interested in investing the time to learn the ropes in GvG. It is this learning where camaraderie is built, relations are formed and money ends up being spent.