that price is high for even a rebuild, imho.
how long will it last, forever if you do not drive it.
btw, i think i have already answered this; on another site maybe?
a used trans runs $400 - $800, labor about the same.
you can be back on the road for $1000 - $1500.
but if it runs , it runs, drive it.
if you need a reliable car for the hiway, replace the trans .
if you are just going to the store and work or school, drive it.
the only extra expense associated with it breaking down suddenly is the $60 - $80 tow.
the used trans and labor will be the same.
but if you have time you can start looking for a trans, and a shop, and buy when you find a deal.
you could find a trans close to home for $250.
the guy i sold mine to did.
put in your zip aand sort by distance to see what is close, easy.
then sort by price to see if there is a bargin to be had.
shipping will probably add $150 to the price.
one more thing,
it is WRONG to compare the cost of the repair to the value of the car.
it is RIGHT to compare the cost of the repair to the cost of ''replacing'' the car.
what would it cost to buy another car in the condition yours will be after the repair.
usually another car is more expensive.
but some times it is right to move on and start over.
only you can know that .