From that photo, plenty of meat left, maybe 50-60% worn
if the whole reel is like that it has many more light grinds left in it. basically its stuffed when you are nearly down to the round spiders that join the blades.
Other factors that need to be taken into account is if some welds are higher (if it hit something and was re welded), if there are rock nicks in the blades, you have to spin grind all blades back past the lowest problem. do that a few times and you dramatically shorten life