Workday is not an ERP? Beyond that, they're effectively replacing major stacks of traditional SaaS tools with in-house ones. Considering the scale and complexity of what Klarna does and the regulations it has to follow across many different markts, I'd say its a valid concern. Now, I don't think SAP etc are going anywhere, especially in traditional businesses where most of the company is reliant on it, but it seems there is a way to do it.

That said, plenty of banks still run on mainframes and use COBOL.

https://www.salesforceben.com/klarna-salesforce-workday-part...

Well lets see how it works out for them - they're ending the partnership for HR software in order to build their own, but they say they haven't built anything yet!