It's been mentioned that H&M have trademarked a bunch of things, which is being interpreted as their intent to monetize their royal connections but trademarking is also used by companies and celebrities as a defensive measure to keep other people from making money off them. Which is only smart and all things considered, probably a necessity.
Honestly though, as an American I don't have any interest in who pays for what. (I can see why the Brits do.) Harry is always going to be grandson/son/brother/uncle to the monarch, so security needs and other expenses are never going to completely go away. PC can afford to subsidize it.
I am interested in seeing if H&M can pull off a life contributing through their charities and other ventures while staying sane and maybe even a little happy.