Timing chains normally last the life of the engine, and do not need to be replaced.
There are instances when a timing chain goes bad, but they are rare. Very rare in your case. If the chain were going bad you'd hear it. You don't report any problems, just a recommendation to change the chain based on age/mileage.
As I said last night, check the maintenance section of the owner's manual. If there is a replacement interval for the chain it will be listed. It's not listed because there isn't one.
The 3.0 Nissan V6 has a reputation as an extremely reliable engine.