What if the customer's won't migrate? What are they going to do then? AFAIK, they cannot force the customer to migrate from their own hardware to the cloud. I agree that the cloud's greatest strength is that you don't need to host applications on premise...but that's also it's greatest weakness. What if there's an internet outage, or the cloud goes down? At least with on-premise servers, you can still get work done. Case in point: Microsoft Office 360. They have had a couple of high profile outages in recent weeks.
Then there's the security issues as well. If something get's put in the cloud, there is no guarantee that it will be secured. Look at all the reports of unsecured databases being discovered in the cloud. Then there is another exploit source: SAP themselves. If people think that SAP won't look at the customizations that their clients have made, think again. They will look at each one, evaluate it, and then incorporate it into their offerings to make money on your code. Furthermore, you will be prohibited from using your own customizations once it conflicts with an offering. I haven't checked, but I'm quite sure there is a clause in the license that allows them to do this.
SAP is an example of a company that has really outlived their usefulness and has become a money pit of software vendors. It's throwing good money after bad. No amount of cash is going to fix the inherent problems with their software either. After a certain point, you will have to cut your losses and run far away.
Biting the hand that feeds IT
