The stay in Paris is a temporary thing - he’s got a 3/4 year posting at the Danish Embassy as Defence Attaché. He was originally only supposed to be there for a short time while he did some prestigious course. In an interview his wife alluded to the decision for them to stay for so long not being entirely their decision. It was an odd one given he’d had a serious health scare after having a blood clot on the brain.
He has said that the original plan that he was informed of in may his children would lose use of their Princely titles as they each turned 25. However that was changed to all of them losing them at new year.
It’s very odd. Especially as both he and his sons say they heard the news from a palace official, rather than his mother mother herself.
It hasn’t helped all the speculation about the fact that his wife, Marie, and his brothers wife, Crown Princess Mary, despise each other and that the Crown Prince couple are very keen for them to actually stay in France for good.