Google/Bing 'the decline and fall' and you will get an alarming list of historical perspectives. What goes wrong? What makes big (the empire) so non-sustainable? Must it decline? Must it fall? Talk to many people in large organisations and their perspective often seems to be 'yes': their continuing allegiance is simply because of the pension and the hope of a bounce in the share price.
How do you reduce Edward Gibbon's masterpiece (don't even consider the abridged version) to a word or two? It's complexity. When it gets big it gets complex. And when it gets complex people lack the confidence of exactly what they are meant to be doing, the simplicity of purpose, the simplicity of communication and the simplicity of execution. And above all the simplicity of accountability.
At the next board meeting, ask: what can we make simpler? Not simplistic-anyone can do that. No: what can we make simpler? And then there may be ebbs and flows but perhaps no decline and fall.