Replace Active Directory with AAD and Intune

Of course you can.. Legacy apps are always the bottleneck. When you don't have those ones. It depends on how many users you have, but I will advise you to split things up. First you can start with migrating your identity to azure ad by installing azure ad connect first If there is a on premise exchange server left --> move it to exchange online! After your email and identities are mgirated you can migrate your devices to azure ad, of course use autopilot. After your devices are migrated , migrate your devices! https://call4cloud.nl/2021/03/deliver-us-from-hybrid/