Provide a better way to handle the project key migration

Since we've ended project key format support on JIRA 6.

1. Is it possible to provide an update task for the user who is using the customized project key to migrate the project key to the normalized project key?
2. Also the measurement regarding to the project key using in the remote link to other application?
3. Is there any exception character and symbole that the user can continue to use?