We need to develop a migration path from "OpenMRS 1.9" (the most common deployment at the moment) to "Platform 2.0 + Legacy UI module". Giving implementations a well-documented helpful hand in making this transition will be critical for getting implementations to adopt Platform 2.0. While a fully automated solution would be great, this does not need to be fully automated. A combination of semi-automated steps and wiki documentation under the Platform 2.0 release notes would suffice.
For those using 1.9, the should start with https://wiki.openmrs.org/display/docs/Prepare+for+Upgrading+From+a+Pre-1.10+to+1.10+or+Later+Version