I have a 2015 I bought used Oct 2017. It was off a 3 year Lease and bought at auction by a LEAF flipper in California. It came with 12 bars, clean, no damage, complete, but after 6 months dropped to 11 bars. It stayed there for three years. It dropped to 10 bars 6 months ago. At this point I have had it for 3.5 yrs. I plan on keeping it for as long as it is practical. It is a second car for grocery runs and errands. If I can get another 6.5 years (10 yrs of use) and sell or trade it in for something more than salvage with the original battery it will be a success. I estimate at that point it might be 8 bars and 50-60 mile range? So between now and 2025 I will likely sell it and be done with electric cars altogether, unless a Kona, Mustang can be had at a reasonable price. I will never buy an electric car that does not have active battery pack cooling. In fact this may be my first and last electric car....
Again this is a second car, so I am not in the market for a battery pack with a solid 80 mile range. My DREAM would to get a 40KW pack to replace the 24KW. I think that is possible without too much heart burn, with conversion kits and advice available. Oh part of the dream is get this low mile pack cheap... So that is unlikely.
BTW I asked Nissan about a battery replacement right before I went out of 5 yr battery warranty. It was with parts, labor, tax $9000. That is for a 24Kw pack and no chance they would put in a 40Kw pack.
The other option I considered is rebuild the original pack with the best original and replacement cells I can get. My pack cells are all fairly well matched, none are failed, but some are stronger than others. Right now I am at about 80%. Years ago I saw people parting LEAF packs out. People use them for solar cell power or other non LEAF projects. Of course time and effort and ability to find good individual cells at a good price is also a long shot. Plus the removal, disassembly and reassembly of the pack is a big job,
I have looked at salvage auction sites and have been tempted to buy a wrecked LEAF.... I could part it out and keep the battery pack. However you don't know the history of the pack. Also I know of people who bought wrecked Tesla's years ago, in hopes of getting the battery, only to find out it was gone, already removed. Then the hassle of parting it out and selling the parts is time consuming. However it could be the path to a cheap battery.