It’s almost always much tougher to estimate when production of anything ended than when it began. A product launch is accompanied by fanfare in the press and applications for trademarks. Dropping a product is a much more furtive and occasionally intermittent process.
For what it’s worth the City de Luxe appears in the 1969 RTDA almanac, and is gone by the 1974 edition (I don’t have access to the intervening years). This would suggest production (or at least availablity in America) stopped in the early 1970s. On the other hand Jacque Cole’s article in the July 1982 issue of Tobacco includes a brief mention which implies the City de Luxe was still being produced at that time, in both England and France. Other than that brief citation I haven’t seen anything referencing the line after the 1970s.