There have been some rumblings about keeping the old Jaffa - Jerusalem Line in operation as a tourist railroad of some sort.
I think running anything to Jaffa would be impossible because the continuation from Tel Aviv to the original Jaffa terminus was abandoned several decades ago The reason for the abandonment was apparently that the city of Jaffa had their eyes on the land. So I expect it has long ago been put to other uses, which probably means built on, in other words, that line is not coming back, not even for tourists. Apparently the old Jaffa station building is still there and in some sort of use, although I've never seen it myself. Apparently a short peice of track has been put back to remind people of its former use. One day the Tel_Aviv light rail / metro might go there.