Look at Perdan. They made a comeback even after getting their asses beat to pulps. Sometimes you just have to suck it up and wait for the right moment.
I would like to see that happening more often than it does now, that's the idea of the proposal.
I don't think your system allows that to happen. It does not change the fact that:
1) Players don't *want* to be vassals, so won't choose the vassalage option
No, it takes that into account. For a realm to expand it has two options: it either fragments itself or it grows into an Empire with a center of power and tributary states. Regardless of which, both choices create much more unstable situations, making conflicts and war a much more realistic possibility.
2) Players often want to be very punitive, and impose extremely insulting and unpalatable conditions on defeated foes
And the idea is for them to be able to impose insulting and unpalatable conditions (such as the proposed Vassalage is), but avoiding them to be
permanent ones (such as 99% of the current proposals are: territorial gains).
3) Players find it almost impossible to accept these extremely punitive conditions
Because there is usually no way to come back from them. If the winning realm eats a large enough chunk of yours you are stuck as an undeclared vassal forever. If it only takes part of your income for as long as you cooperate (because it cannot eat your land nor wants to colonize it), then the option doesn't get that ugly.
Instituting an option that garnishes X% of a realm's income to send to another realm as tribute does not seem to me to be something that will change any of those facts. If Realm A can't take all of Realm B's lands, then it can drive them rogue, and then replace Realm B with Realms C and D (as happened with Ibladesh).
Yes, that is one of the possibilities, which will not always be the one conquerors want. Astrum wanted Caerwyn to remain, just without Golden Farrow. Luria Nova didn't want to destroy Fissoa, just make it a vassal. As that was impossible from current game mechanics after the war they merely turned into "associates" of the Lurian Empire. And so on.
Right now we seem to have only two acceptable options: Total destruction or return to status quo ante bellum with very little modifications. How about we add a third?
