Sure, after you reengineer your application. Even then, "serverless" apps often use persistent resources like databases, and your developers will likely spin up those resources for the same reasons as indicated in the article.

Cost savings can be incredible if you use the FaaS product in the most aggressive way possible. For us, this means using functions as a simple translation layer between SSR web forms served directly as text/html and whatever SQL provider (ideally also on a consumption-based tier).

90% sounds just about right. We are seeing figures going from $120/m for a VM-based QA environment to $10/m for a consumption-based / serverless stack.

(CEO of Neon)

We routinely see 10x savings when switching from RDS or Aurora. Especially if you start adding dev environments.

depends on what your utilization looks like, serverless is usually +/- an order of magnitude more expensive. Ideally your workloads are stateless and containerized so you can shuffle them between serverless, container orchestration that you own and dedicated VMs.