This would be neat for thematic reasons, but if you are fed, your only counterplay would be CC. They would have to CC you before you get close to them so as to pop your ulti before you get to the Carry. If you were to get to the carry, then it would be essentially a free kill on the carry.
Also there is the other side to this coin. Normally, a kindred will build DMG to be a part of their team's backline and use their ult to protect and peel. If this change happened, she would have to sacrifice a bit of dmg for durability so as to keep her alive while going in as more of a bruiser kind of champ.
Very cool thematic wise but probably very unfun to play against or even with.