In reply to Euan McKendrick:
Will be a big shame if the company are willing to say that the lifespan for metalwork is essentially forever but aren't willing to re-sling older Friends or Rockcentrics. There will be a lot of disappointed Friend-owners out there (myself included, I have a size 6 and a size 4 which fill important spaces in the current range). Black Diamond will re-sling old Camalots and DMM will re-sling old 4CUs.
They're really shooting themselves in the foot; I'll likely replace my Metolius micro-cams soon and even though the Zeros are my favourite out of Dragonflys, the new Mastercams and the old X4s (I've not tried the Z4s), I'm really not sure I'd buy them.
Jon R, it's far from ideal for a full rack but if it's just one or two, you can cut the old sling off and use a loop of dyneema cord (https://www.dicksclimbing.com/products/beal-55mm-dyneema-cord-per-metre). As far as I'm aware, this is fine with tech friends (not so much with cams with thumb-loops) as they have a captive eye. Make sure you use a triple-fishermans and leave a bit of a tail.