Having identified the true root of the problem, I would recommend directing resources towards dismantling advertising. Focusing on anything else is wasted effort.
Also, capitalism doesn't need perpetual growth either (anymore than other system, that is). Independent and worker-owned media are still facets of capitalism, for starters.
That sounds self-contradicting. How do you define «sustainability» in that case?
If you take «growth» to be defined as d(something)/dt>0, I’d posit that any equilibrium by definition has zero net growth, whether it’s a static or dynamic equilibrium.
That said, in long run, there's both a tendency for most growth to fall and for basically nothing to be sustainable.
We can stop any time, now. Money was already a satisfactory root cause.