I don't see the open source community, as we understand it today, under taking a SAP replacement either, what I'm thinking is that the business IT community ( for lack of better terms) starts adopting open source tools, standards, methods, philosphies, and as an outcome, expands the open source community and its potential.
I'm saying that the open source community would grow because the rest of us start participating, we would use these tools to solve our own problems, one of them being the outragous cost of enterprise-wide technology.
I agree that we have to change the fundamental business process and I think that part of that change is how we think about and use technology within large organizations. My experience of large organization is that IT is executed in a top down fashion. Quite frequently the TOP is furthest removed from the practical everyday execution of technology and the TOP limits what is possible within an organiztion by their understanding. Open source is bottom up, trying to use that approach would be radically different.
I don't know of anything bigger than SAP when it comes to enterprise-wide commitments, I believe it's the ultimate top-down decision, which is fine if that's the only way your company can run, but it's the old industrial-revolution model we're talking about not the information age revolution we're living in. Where's the next competitive edge? As much as SAP is trying to morph, I'm just not convinced, too much baggage.