2002 Nissan Altima Fix or buy new

Over the past six months or so i've had to add oil to my car every two weeks or so. Recently I brought my car in because the service engine light was on. They told me that I blew a head gasket ($1600 repair). Because of the oil consumption history of my car they suspect that there may be other problems and I'll probably have to replace the engine ($4000). I hate to do this since my car is not even worth that much however I cannot afford to buy a new car. I want to know if I do replace the engine what other problems good go wrong with car after this. (Transmission, radiator, hoses, etc). I'm just trying to see if it would be worth fixing the car.