First, it's not an accident that this happened two months into the COVID lockdowns. Seattle PD seems to be doing much better than 10 years ago, and yet nothing happened back then and we see lots of protests now. People get more anxious being afraid of the illness and from sitting indoors with 1/8th of the usual social contact, and with unclear job prospects, so they are more likely to act on this anxiety. The summer will turnt to fall, the Woodstock will end, the COVID will recede, the anxiety will subside, and the need to earn money will come front and center again.
Second, the kids will grow up and move on. Some people will never grow up, but it's not the same numbers. The next group of kids will have another cause to fight, for the simple reason that they will not be caught dead practicing anything done by the "old people". In fact a key element of all protests is the desire by the young to distance from the old in order to find their own place under the sun. This dynamic is fueling the protests now, and this same dynamic will undo the protest movement.
I appreciate your point that marketing is more about movements today that it was earlier. Still the capitalism has turned Che Guevara into a T-Shirt franchise, so it can go either way I guess.
It could still be that you're right and I'm wrong, but I think it bears listing all considerations.
However - the kids will be replaced by other kids.
'Social Protest' - I believe is actually a form of normal rebellion.
As kids grow and they come into their own identities, at some point, they have to rebel against something. Kids who are abused rebel really early in life. Kids with their own identity rebel in HS. A lot of 'well-raised kids' don't rebel until University - and this rebellion takes a more intellectualized form.
'Youth in Revolt' is perennial, it's metastasizing now because of the possibility of outrage.
That said ... Baby Boomers were considerably more outspoken than their progeny so perhaps whatever comes after Gen Z will be more chill.