MDL-48715 we made it possible to move custom lesson activity restrictions to course completion conditions.
MDL-26689 - we hid those old conditions to new lessons, and added a warning to old lessons with the old restricitons added.
Following on from those we should automatically update all the old lesson activity conditions which can be converted automatically into completion conditions.
That will leave us with some which lessons which we will not be able to automatically convert the conditions.
Ideally with those left, we would have some admin tool which could list the lessons which some manual action is required.