S/4HANA was launched in 2015 with the biggest marketing campaign in enterprise software history.
The CEO called S/4HANA "The fastest growing product in SAP history".
Yet to date, not a single large SAP customer moved from ECC to S/4.
Not a single Fortune 100, 500, or even 1000 ECC customer has adopted S/4HANA.
SAP services teams have been working non-stop with half a dozen F1000 SAP customers for years. None of these pilots came to life. They all failed to move a single customer to S/4HANA.
SAP can't get a single F1000 reference for S/4HANA after 4 years of general availability.
The reason is HANA.
The complex re-platforming, code remediation, data migration, cost, risk, and lack of resources.
All of this because SAP decided to kick Oracle and IBM out of their accounts so they invented their own database for their own applications.
What's worse is that SAP's acquired applications still run on Oracle not HANA. SuccessFactors was acquired in 2011 and still runs on Oracle. The same applies to other SAP apps like Ariba, Concur, Fieldglass, and Hybris.
HANA was a bad bet.