Comment by Shekelphile

tbh, it still isn't economically feasible. spacex 'cheated' to achieving reuse by just making the the entire plumbing and engine assembly bolt-on to the lower stage on F9 and they just replace that every time one is 'reused'. to my knowledge, they still haven't reused an engine without either replacing the nozzle, turbopumps or both, which are so expensive that reuse might actually cost them more money in the end for the benefit of faster turnaround times in years where launches are booked heavily.