The wolf shall dwell with the lamb, and the leopard shall lie down with the young goat, and the calf and the lion and the fattened calf together; and a little child shall lead them.Isaiah 11:6, English Standard VErsion
We are far closer to that day today, than we were 2,000 years ago.
Give it another thousand years or so, before it happens in time on this earth as an unremarkable fact of life.
No more shall there be in it an infant who lives but a few days, or an old man who does not fill out his days, for the young man shall die a hundred years old, and the sinner a hundred years old shall be accursed.ISaiah 65:20, ESV
There is still sin and death, so Christ has not returned yet during this predicted time.
But already, people are called “young” when they are in their 30s and 40s in the West. Give it another two centuries or so, for this prediction to come to pass.