honestly past 12 mos. IMO I don't see why breastfeeding would still be necessary. Not trying to upset anyone, just my opinion.
It comes in handy if your child isn't able to drink cow's milk. Alternatives are expensive and don't necessarily cover the same nutritional needs. My kids were small and didn't take to cow's milk immediately, so until they were eating enough foods that covered those needs, those wake-up and bedtime nursings were still important for them.