When the war can't be declared in the first place, there's nothing to end. More importantly, think any war targets are going to be able to chase down every little hidden structure the aggressors have? Some random POCO somewhere, a back-up structure in a wormhole, maybe pay for blue with Goons and drop a Citadel within Fortress Delve or whatever the fuck? Hell, make it a Fortizar somewhere and see how many war targets are willing to even be on grid with it at any point.
The number is likely zero.
The supposed problem is that wars chase people out of the game (Unproven hypothesis, most likely far from that simple and part of a far more complex problem to solve) and attaching structures to that doesn't change that one bit. In fact, you think anyone who pussies out of Eve over a wardec is going to form up no less than three times on a grid controlled by the enemy, with structure support, at a time decided by the enemy and quite likely not even the only structure needed to be taken down? They won't even undock because the war exists, much less take on the enemy where they're strongest.
The solution isn't tying it to structures, which is a fucking moronic idea to begin with. The solution lies in providing counter-play and incentives to be active during a war. Imagine the war between me and ARC if there'd been an 'end the war through activity' type mechanic in play.
I scout and chase ARC... well okay SFRIM people 99% of the time but let's call it ARC for now... people around, hunting and occasionally killing them. This is undesirable to them, so they organize, knowing that if they... say Mine X Amount Of Moon Goo, or collect Y Amount Of NPC Bounties or Explore Z Amount Of Sites or Produce So And So Much Value And Manage To Trade It and whateverthefuckelse bears do with their time the war will end because of the mechanic that says "aggressor incapable of pursuing an effective path towards their victory conditions, war declared unsuccessful, defender now have X weeks of war immunity from those involved in this war" or something. They succeeded in this since they organized, scouted and watched their aggressors, coordinated their bearing and maybe even defended it and so on.
Same thing on the offensive side with war goal mechanics in play. Declare war, mechanics look at aggressor and defender and determines some upper and lower bounds, then the aggressor gets to set some war goals like "X amount of destroyed structures, Y amount/value of destroyed ships" and so on. Upon successful completion of the objectives, war is declared won/lost and those involved can't be at war again for a certain amount of time. Add some reward mechanics to both sides for succeeding in attacking/defending (whether it's through fighting or successfully remaining active while avoiding losses) to incentivize activity and you are starting to get somewhere.
It'd ensure that the only way for it to become a forever war would be if both sides remained inactive, and the best way to end the wars would be to be active. One way or another. It'd encourage coming together as a group and it wouldn't be so incredibly easily cheesed as 'toss random structures around where they're incredibly hard to find' and so on.
I wonder how many people are going to forget to tick that "automatically refuse structure transfers" thing. I bet there's going to be a bunch of people finding out they suddenly own property in WHs and other hard to reach places, making them wardec eligible anyway.