They do need a touch up every odd year, depending on usage. Have been fixing about 100 players over the last decade and seen quite a lot of different faults. Cables, light bulb and pitch always goes sooner or later. In that order of frequency. Then there's the rough treatment leading to broken tonearms, lost on/off caps, smashed on/off housing, buzzing transformers and every odd year, faults in the electronics. When there's too much wrong they end up as parts bins. It only happens as accidents to normal people. Clubs have so heavy usage that may end up replace them every some year as an alternative to constant repairs of old players.
Many disappear without dying, collecting dust. New DJ's pop more often than old DJ's sell their players. And so on.. I see no reason to expect the demand for new production of these players to vanish. It may decline over the years. It'll still be a long time before the need for new ones disappear altogether.
Have seen some 3's and one 5, the rest have been mk2's. They can ditch the rest as long as they keep up the mk2 production!
A funny thing is the regional default in the colour. 1200's (silver) is default in America and 1210 (black) is default over here. Often makes the least common one seem more special where it's not the default.
PS: I love these turntables! One of the best pieces of engineering ever. A joy to repair.