Zara and Mike will never ever get involved in royal duties, except showing their face at a Royal garden party or in a carriage at Ascot. They lead a very charmed life, they spend a lot of time in Australia and to be honest they are not the slightest bit formal or royal, like royals do it. Have a look at pics of them in Oz! And do we really want an ex rugby player podcaster with a bit of a dodgy past doing royal duties?
And didn't I read somewhere that Louise has already said she doesn't want to do royal duties? Or maybe Sophie hinted that, can't remember.