To keep it short...
Until it's undrivable. Wether it be that I can no longer drive, or its crushed in some way.
But longer version-
Got my B13 4door XE 5speed as my high school graduation gift from my parents; Sort of, since I later payed them for the cost of the car. I've had it for a year and a half now, and just recently got rear ended at about 30mph but its still my daily and I'm waiting for my $ to pull the trunk and fix the crack in the frame rail.
Other than that thanks to this community I came to love my Nissan and have even bought another B13, 92 NX
Like I said, I'll drive them until I cant anymore. No plan on ever selling.
Too much pride, money, and time invested to make it worth anyones offer.