hmm, that's very worth consideration actually. While I'm against "style creep", people often become attached to features of other games and like to re-create them in their own games, and "capturing" animals for livestock was/is a big part of some AOE scenarios, as is hunting -- being able to kill a creature and harvest the meat for food. One could just say to do it in lua once it's in, but I'm thinking that it's worth of consideration for integration into the engine its self, as long as it can be kept simple.
However, note that stability and multiplayer is top of the list right now and is still not under control.
None the less, here are my thoughts.
CapturingI proposed this idea long ago for the FPM Lich, but it never made it's way in. It basically involves the ability for a unit of one team to take control of a unit from another team. For my proposal (for FPM), I wanted to limit the number of units the lich could control, give enlightenment a mechanism to retake control of their units and give the controlling faction a kill for the death of the controlled unit (and the original faction a "death") -- so the state of the controlled unit (having been originally from another faction) is never lost. Additionally, there is a master/slave relationship between the lich and the controlled unit that should be lost if the lich dies (or perhaps even if he is stunned, paralyzed, turned to stone, etc.) In fantasy lore, there are often spells used to control others, so it's more than possible that such a scenario could pop up again with somebody else's mod.
As for the "animal tamer", they would probably want to execute some skill (like the lich) to gain control of the foreign unit. But for AOE-style livestock capturing, it's an implicit action that occurs when any unit comes near the foreign livestock unit. So if I do this feature, I want there to be a well thought-out framework that will accommodate all of theses scenarios. Also, for the animal tamer, they may not want to maintain the same master/slave relationship that FPM liches do -- so once an animal is tamed, it stays that way and the tamer can go on to tame as many animals as they like, get killed, etc.
HuntingSome others have already requested the ability to transform a unit when they die, this could extend upon that functionality. Essentially, it would transform the unit into something that's harvestable (optionally with the slowly decreasing resource count as in AOE).