I am a consultant, and when I go on-site, it's to determine how they can move to the cloud. Often, clients want to migrate because everyone else is. Others want to because they assume that they are going to save money. They will require less support staff in-house and they won't have to purchase servers.
Customers have a need to cut back on expenses, and equipment. Their servers are becoming obsolete and are required to update their licensing. Rather than doing that and creating a larger overhead, they look into Microsoft Azure. It might be a better way to go and it's less money upfront.
Some clients have already implemented VMs. A lot of their data is stored that way. There is a difference when you move that to the cloud.
If you share it back and forth, you have your hybrid where you have it in the cloud and on-premises. It depends on the company and what their plans are.
There is an automated tool that you can analyze your data sources and identify whether or not you can upgrade them and you can also use it for SharePoint. I've used Azure for that purpose.
In regards to data warehouses, I'm doing the upgrades from on-prem to in the cloud, or a combination of both.