No doubt they made some mistakes, but it wasn't for lack of trying.
(And having debugged code on an ia64 I'm quite happy with the status quo!)
As we move into an era of 'I don't see why I should get a new machine' of growth minimization there is a window for folks like ARM to get in with 'all day computing.' But it will take someone extraordinary to make that happen. Look at the state of Linux on ARM to understand the power of a legacy architecture.