This is a bad idea imo, and the departure of Harry & Meghan demonstrates why. When the working royals are limited to just a few key players, if one or two of those players is taken out due to death, desertion, health or scandal, that deals the royal family a huge blow, both in terms of the unique personalities left to engage the public, and in terms of weighing down the already busy working royals with even more work. It just exposes how vulnerable the royal system is to the caprices of individual personalities.
Whereas, when you have a sizeable royal family, a lesser royal can always step up and take a bigger role. But if that person is busy leading a fully non-royal & privately employed life, they won't be in a good place to step up if needed. British society will have to adjust to having less of a royal presence at public, sporting, cultural and charitable events, and the royal family will gradually become less relevant.
The royal balcony looks anemic with only a small handful of people standing on it. I think it's fine for the royal family to be and look like the full family they are, and not limit it to a few figureheads, which is what Charles basically plans to do. He should re-examine that policy after witnessing the departure of his son and daughter in law, who were supposed to be two of the few key players.
Anyone else notice a bit of self-interest in Charles wanting to slim the monarchy down to basically him & his direct heirs after the queen dies?