Harry is the son of the King (soon enough). Of course he is an HRH. So is Archie. And MM for as long as she’s married to Harry.
The “not using” is a way to ensure they can do their do-gooding without it reflecting on the monarchy. So, if they want to pitch up in jeans and a jumper; if they want to choose which causes they support; if they want to do nothing for 9 months of the year; if they want to spend stupid amounts of money on holidays and private jets - none of that is how the RF does things.
It’s all about protecting the institution, but also keeping Harry and Archie within the fold, as they are humans after all.
Which means H&M are free to do as many, of whatever engagements they want, for as much money as they want, which they can either keep or put into this foundation. There will be zero transparency. Donations will come into the foundation; H&M will be paid “expenses and emoluments”, and somehow we’ll see them wearing couture, living in fancy homes, taking expensive holidays, fraternising with celebrities in a most un-Royal way.
They’ve put all their eggs into their own basket. They’re so convinced of their own power, their own star value, they think they can go it alone. As people, though, who are they? The grandson of the queen and an actress who’s a hustler. People of substance, causes and charities of substance, will soon tire of them. They will become hangers-on as they have nothing to contribute. Being representatives of the RF is all they had (hence Fergie and Andrew and Sophie and all the others before and since flogging themselves for cash to the highest bidder), they’re all just mediocrities with nothing else to offer. HMQ and what she represents is where the money and the power are. Not Harry and Meghan Markle.
HMQ has let them out for as long as they want. They’ll be welcome back in time. I think once the dust has settled, once they’ve completed their family and they’ve lived this separate life for a good few years and they’ve discovered just how difficult it is to make a buck the way they want to, they may well come back. I think it’ll be years and years before all the hot air that’s been blown up their asses disappears and they see just how little they have to offer.
Also I think it’s in very poor taste to speculate on how long a marriage will last. Talk about wishing someone (Archie) ill.