Guild Wars 2

This won’t solve any of the massive structural flaws of current WvW design, but will at least slightly improve some of its elements.

Summary:
Conquered enemy supply camps do not generate supplies for nearby friendly-controlled towers and keeps.

Definitions
Friendly supply camp: the two supply camps nearest to your server spawn point on the EB map and on the two enemy borderlands.
The three northern supply camps in your borderland.
Enemy supply camp: any other supply camp.

Proposed change:
you can still conquer enemy supply camps as usual, they will give their usual 5 points per scoring tick and players will still be able to get their 10 supplies from them whenever they are not empty.
However, no matter how long you hold them, they will never generate dolyak caravans for you.
The only way of getting supplies on “conquered” keeps/towers in “enemy land” is to escort the dolyaks from currently held friendly supply camps all the way to the destination tower/keep.
This obviously implies the current dolyak paths have to be changed so that dolyak are “smart” and modify their path depending on how many points you control. To reduce the complexity of implementation, you could further restrict supply routes by e.g. ruling that the “left” friendly supply camp can only supply the left half of the map and the right friendly supply camp can only supply the right half (and both can reach control points situated in the middle i.e. garrisons and Stonemist castle).

Why it slighty improves the situation:
it puts an higher focus on logistics and allows for a server to become overextended, something which is currently impossible simply because the overall map travel time is too short so that 1-2 roaming zergs will defend all your territory pretty effectively, no matter how big it is and how many control points you’re holding.
It also gives a “home turf” advantage to the servers on the zones closest to their spawn points, thus making total map control slightly more difficult.

It won’t do anything for a 30 vs 0 vs 0 nightcap problem, but it could slightly improve the 50 vs 10 vs 10 situation by making it a little more difficult for the 50 to fully upgrade and resupply the keeps and towers farther from their base.