Options
A: Evolution
Preserve backwards compatibility
B: Clean Cut, Reuse Architecture
Migrate to Cocoon 2.2
Replace content repository with JCR
Start with minimal core
If possible, replace home-grown stuff with out-of-the-box components (a lot has happened since our components have been built)
Identity management: no internal user storage (maybe proxies), SSO support (OpenID integration etc.)
Workflow engine
GUI framework (GWT, Dojo, ...)
Migrate modules step by step
C: Clean Cut, Reuse Experience
Reconsider all requirements thoroughly
Derive architectural constraints
Choose architecture
Reuse code where it makes sense
Requirements
Automatic content migration
Architectural Constraints
No changes to URL space and URL-document mapping required
Workflow-driven content manipulation
Access control on repository level - permissions assigned to content objects rather than URLs