I think we'll see a reduction in complexity and an increase in transparency, rather than just on-prem.
One medium-sized server can now easily serve the entire banking system of a large country. So you don't need clusters of servers with careful tradeoffs between consistency and availability because of the CAP theorem.
Just get a big honking host, slap Postres on it, and run your application server in a VM on the same host. For backup, export the WAL logs from Postgres onto your favorite off-site blob storage. UI for it? There's Pigsty.
It still makes sense to host this in a cloud provider, just because you probably don't want to deal with actual hardware. And maybe get a second standby server for redundancy.
That's it.
You'll need a bunch of external dependencies for email, 2FA, observability, LLMs, and so on. But they should all be outgoing dependencies that should not allow access back into your system.
One medium-sized server can now easily serve the entire banking system of a large country. So you don't need clusters of servers with careful tradeoffs between consistency and availability because of the CAP theorem.
Just get a big honking host, slap Postres on it, and run your application server in a VM on the same host. For backup, export the WAL logs from Postgres onto your favorite off-site blob storage. UI for it? There's Pigsty.
It still makes sense to host this in a cloud provider, just because you probably don't want to deal with actual hardware. And maybe get a second standby server for redundancy.
That's it.
You'll need a bunch of external dependencies for email, 2FA, observability, LLMs, and so on. But they should all be outgoing dependencies that should not allow access back into your system.