If I were you I'd go for a toyota. 2012 and up. They are built reasonably well but also very uniform and because of that they are easily and relatively cheaply repaired.

If you keep up with maintenance you could theoretically drive one your whole life

Depends on the year, model, etc. I usually like to check similar make/model/year to see what kind of long-term mileage they get in comparison. For instance, if it was a 2015 Nissan Altima, I would check other 2015 Nissan Altima's and how many miles they are getting.

6k is low miles for any vehicle, and depending on the year, I would be suspicious. People should average about 10-15k a year with moderate driving. Make sure the title is listed as "clear", anything else can indicate it might have been in an accident or something else.

Manufacturer recalls do not have expiration dates, and any dealer would need to repair free of charge. I had a POS 10 year old Dodge mini-van with a recall, and when the part failed, it was a free fix.

If it's on a recall list the fault should be fixed by the manufacturer at no cost to the owner.

With that low mileage and due to it being a safety issue there should be a recall and free repair by Nissan..

Should still be under warranty

Yes, it's an easy fix and it's free from the manufacturer..
Any dealer can do the service..

If it's being sold by a nissan dealer, they should fix it before you take it home..

That can be addressed by attaching a 16lb bowling ball to your keyring.

Well all cars and trucks break down the older they are.