there are many things that Impact “Architecture Change Management” or “Architecture Cycle Initiations” some of them as per my knowledge are
1. Changes in Business Dynamics. e.g Adding new Lines of Business
2. New Mergers and Acquisitions,
3. Technology getting Outdated.
4. Cost Cutting or Re-budgeting Infrastructure Expenses .
5. People Practice Initiatives.
6. Enterprise Security Requirements.
7. Regulatory and Compliance Requirements. ( New Laws )
8. Customer Satisfaction which Drives Business.
9. Inefficiency of Existing Architecture to cater to growing Business Needs.
10. Business Re-alignment , Major changes in Business at Enterprise Level.
James Smith's Blogs 
there are many things that Impact “Architecture Change Management” or “Architecture Cycle Initiations” some of them as per my knowledge are
1. Changes in Business Dynamics. e.g Adding new Lines of Business
2. New Mergers and Acquisitions,
3. Technology getting Outdated.
4. Cost Cutting or Re-budgeting Infrastructure Expenses .
5. People Practice Initiatives.
6. Enterprise Security Requirements.
7. Regulatory and Compliance Requirements. ( New Laws )
8. Customer Satisfaction which Drives Business.
9. Inefficiency of Existing Architecture to cater to growing Business Needs.
10. Business Re-alignment , Major changes in Business at Enterprise Level.
Regards
James