I've suggestion for you to make a (test) server with fixed entry fee (for example 50EUR/month until ww's are released) which player needs to pay if they want to register on that server. For that players get server long all bonus futures, all building slots, 10 npcs and 10 instant finishes per day (those numbers are only as an example, because having those unlimited would make game uninteresting) and limited amount of silver (let's say 20k as an example).
Why i think this would be good option ? Because players would know fixed expenses they'll have on certain server and what they'll get for that money, but prize most be at some level most people can afford to spend. We'd get multiaccounting away with it, because if someone would want to have multiaccount, they'll have to pay for it to register and risk losing money for all registered accounts if they're caught cheating, also players would try harder (because they pay, now they can choose not to) and whoever would register would play at his 100% which'd make server more competitive and fun with far less inactive players, which can ruin someones game now, for example a king is realying on his governors to do their best, so if 4 or 5 stop playing after few days/weeks it hurts him too, not to mention if king becomes inactive how it can hurt governors.
What's in for you ? I think your revenue wouldn't be so much different as it's now, because EVERY player would pay to play, now i think there're many who don't pay anything and play regualry, i think more people will be encouraged to pay money knowing they'll have same conditions as everyone, not like now, when someone can afford to spend 5k eur/month on travian, other can afford 100 eur (early money makes huge difference). I also think that might bring alot of lost players back to the game (from my information most stoped playing because they couldn't play as competitve as they'd like vs whales due to money issues and game became too much for their monthly budget) also it can attract new players to try the game.
I'm not saying that EVERY server should be started as prepaid, there still should be some left as it's now, so new players can get to know the game for free and than decide if they want to pay money or not. But i think you should try to run few servers like that and see how it affects your revenue (which i understand is most important to you), if it'll bring people back and have servers with 10k people again.
In my opinion that'd be win win situation for TG and players. So please take this under consideration.