Getting the Web 2.0 inside is about knowledge enablement of business processes.
Instead of pushing tools to collaborators, managers should pull knowledge driven behavior from them, this way creating the necessary context that will inspire innovative application design.

Inside the enterprise, communities means collaborators teams of specific processes. User produced content means all the information objects stored across disparate sources of structured and unstructured content. Collaboration means collective case based problem solving using shared information. Information categorization by users means automated extraction of exploration dimensions from information items. Web mashups means the final user ability to build and maintain interfaces blending views from disparate information sources both structured and unstructured as well internal or external to the organization.

I think Enterprise Search technology has a key role in the value chain of the information management process in the Enterprise 2.0 by delivering findability, fine grained contextualization and multi-perspective exploration, the later being the main factor for superior problem solving.

On the other hand, we have to surpass some difficulties related to information confidentiality and security as well to the cultural lock-in that perpetuates the information siloes and privileged power hierarchies.

In my optimistic view, soon business leaders will realize the cost of not knowing: the lack of innovation and poor competitiveness.
Soon people will realize that there is no gain in privileged information, an asset of fast decreasing value in time, and will discover what they would gain more knowledge by sharing information, and by doing so, will be better rewarded.

As to the rest of business and initiatives:
The answers are in the questions.
‘Design Thinking’ (abductive reasoning) overtakes inductive and deductive reasoning in business practices.
ROI is determined only after research or other evidences initiate discovery of design possiblities through ‘why not’ discoveries. And ROI has to be will be measured and adapted for the next estimate.
Current IT methods will be obliterated and replaced with more adaptive models.
The cultural diversity of IT will be overtaken by intellectual diversity — heavier business specialization will superceed other skills, but this will also include fields such as ethnography, psychology, economics.