It may seem like everyone and their mother is using Amazon’s (S AMZN) public cloud these days, but Joyent CTO Bryan Cantrill recently had a conversation with a big enterprise company where the mere mention of Amazon resulted in stone-faced silence. Cantrill initially didn’t understand this stark response, and then he remembered the business that company was in: retail.

Cantrill recalled this episode at Gigaom’s Structure conference in San Francisco on Wednesday, where he gave a presentation about the future of computing. The key take-away: There is no all-encompassing drive towards the cloud. Instead, there are plenty of companies that prefer to keep data on premise, while others mix and match.

Turns out that’s not exactly a new trend. “If you look at the history of computation, it is one of oscillation,” Cantrill said, elaborating that computation has been going back and forth between centralization and decentralization for the last…