How might brands work if there's no intellectual property protection?
Ordinarily, it's hard to know. Most works are protected by copyright restrictions until long after they've lost all interest to the public. That means that by the time you can replicate them and make parody versions of them, nobody's much interested.
An unusual thing happened though with the 'Keep Calm and Carry On' posters. They were made by the Ministry of Information in Britain in 1939 and not actually released to the public at the time. But they only reached commercial success starting in 2000 when a couple in Britain who'd purchased one of the original posters started making copies.
I would have guessed based on my crude reading of what the internet tells me about UK copyright law, as an anonymous work the copyright extends for 50 years after being made available to the public. So by 1989 anybody could make versions of it. Life is never that simple, of course, and as sure as we live in an overlawyered society, some clowns have tried to trademark it, failing in the UK but succeeding elsewhere.
Still, the relatively opaque ownership has made it relatively easy for parody versions to spring up everywhere. 'Keep calm and X Y' is now ubiquitous, for various values of X and Y - Party On, Fight On, Huck On, Chive on (?!), whatever takes people's fancy.
On the one hand, there's a tragedy of the commons effect going on - the life span of the design will surely be shortened as it becomes almost a meme. Everyone overuses it for their lame jokes until it becomes a cliche.
But on the flip side, there are lots of different creative interpretations. Moreover, the design ends up being way more widespread as a result, at least for a shorter period of time.
It's the difference, in other words, between a gold mine where Rio Tinto owns the land, and a Gold Rush on public land where everyone descends to mine the obvious bits as quickly as possible.
You may think that a massive short term exploitation of an idea is undesirable, but you don't even know the half of what undesirable is. Undesirable is the Disney Corporation successfully lobbying Congress to get endless copyright extensions passed so that their damn Steamboat Willie cartoon never passes into the public domain, thereby ensuring that no book written after 1926 will ever pass into the public domain in the US. Man, !#$% Disney. I struggle to keep calm when reflecting on rent-seeking that egregious.
My instinct is to nearly always make copyright terms shorter. When a good is non-rival, copying it is, at a first-approximation, nearly always welfare increasing. If there's a big societal gain that we could be securing by making the distribution of versions of 'Keep Calm and Carry On' restricted to the discretion of its original designers, I can't honestly see what it is.