Here is the method I have come up for keeping an army that eats 5-10 million food an hour. I know it works, as in the past 24 hours my food has gone up, not down.
a) Level 9's and 10's are still viable.
Most people do not know what it takes to farm a level 9 or 10, and few people have bothered trying to learn. You can easily hit one of these each day and get a full load of food and gold most of the time. As members quit or stop producing troops, the number of people who can farm nines and tens will shrink not grow, securing your monopoly on them.
Level 10 NPC towns give you 19 million food every 8 hours, and a load of gold. If your army only eats 5 million per hour, you need only hit 6 of these a day, or 8 if you mix 9's and 10's to sustain your army.
b) Put all your eggs in one basket.
Odds are you had hundreds of thousands of troops and millions if not billions of resources scattered around. That is now unwise for many reasons. Pick a capital city (former level 10 NPCs work best if you are short on scripts, as they have level 10 RS and RP) and move everything there. Cities with maxed out resources do not produce more resources. Every day you should send out transporters to collect all of your resources from your empire and bring them back to the capital. That way they will continue to produce food and resources you are able to sell for food.
10 cities making 200k food and 200k wood an hour can feed a lot of troops if you clear them out every day. Additionally, the hammer city is now kind of worthless. Newbie carebear cities with 18 level 9 cotts are actually superior. The odd that anyone is going to try to cap these is slim, particularly if they have few resources and lots of defenses.
And if you do lose one, cap one of those superior newbie carebear cities close to your capital.
c)No more Miss Nice girl.
The days of letting people with under 150k pres be are over. These people have resources you need to feed your 75k+ Ballista and are unable to defend themselves. Devastate everyone around your cities. If you can, cap their cities and abandon them, every one is a potential level 9 or 10 NPC.
Additionally, remember that carebear cities are now superior to hammer cities. Hitting all the newbies in your area twice a day is a lot like having 30 cities instead of just 10. If they hide/move their resources, you know just who to cap and abandon. If they are not helping you support your army, end them.
Also, the more players you force to quit or complain, the higher the odds Civony will make sustaining your army viable without razing people who haven't yet made the rank of General. Thusly even if you can support your army via NPC farming alone, one should still take a few clicks out of each day hit some people under 200k pres. Complaints brought on this fix. Complaints can make sustaining your army viable once again.
Do not rant on the forums. It is pointless. Let the carebears complain for you.
Through hard hitting attacks, cap and abandon, and cleaning out your non-capital cities once or twice a day you can keep your massive army, and even continue to expand in the direction of catapults, as well as coax Civoney into changing things in a positive direction.
Don't just throw in your hat. It can be done, and it isn't much more effort then NPC farming was. Besides, you will get honor without farming it now. Two birds with one stone.