This is usually a top-down approach and experience shows that communication is an essential part, but at the same time causes the biggest problems.
Of course, strategic decisions are taken at the board level, but don't underestimate that insight from the frontline experts.
Moreover, it is of great importance that people are involved, asked for their opinion and preferably contribute to implementation. How do they see themselves and others in the new organization? What do they think of problems that people may have?
Again good to use the power of personal approach. That is time-consuming, but more than worth the investment.
When architecture is applied, the approach is strategic, but when you go into detail - especially if it is technical - you can only go to one group of experts. These are the same people who are responsible for the every day execution at the frontline.
Therefore it's very important to build a bridge from that frontline to the functional operations.