MT hinted a few years back already that Henri would be abdicating in the not too distant future. After she was basically kicked out of the grand duchy, she has been waiting for Henri to follow her to the south of France... which he will now be able to do as he might remain head of state (so he can celebrate his 25 years on the throne next year) but just delegated all his powers to his son - which for his predecessors was the prelude to their abdication. In terms of timing, the successors were in their early to mid-forties, so Henri is following the examples of his father and grandmother in this as well.
Personally, I don't like the set-up in Liechtenstein at all. Why cling to your position as head of state if you cannot be bothered to do the work... A regency should be a temporary situation not a (semi-)permanent one.