They will still function if they have been under reasonable temperature control, but they will still undoubtedly lose capacity and therefore range. I have a 25mi commute each way and a 2012 Leaf bought today without a battery replacement seems like a pretty big gamble to me. Add to that that I live where winter weather is unkind and I am skeptical of how well old batteries would perform.

From my perspective, battery technology still hasn't proven itself in this regard.