The ownership/sharing profile of data may change significantly in such a situation. So, keeping sensitive information encrypted in the new environment is beneficial. Access can be granted selectively to files and folders as required after actual migration/transfer of control is accomplished.
An Example of Encryption for Data Consolidation
Changing Personnel & Layoffs
Say the files of Bob from company B are to be transferred to an yet unknown employee of company A as a result of the acquisition (Bob may be let go). So, if ownership of Bob’s files are to be temporarily transferred to some individual/admin in A’s domain, it is safer to keep all files encrypted and ensure only no unnecessary sharing/exposure takes place.