Yes, and on a platform that allows for arbitrary logic, like a Turing-complete blockchain, or just a regular server, Lightning-like transactions are trivial. They can be described in minutes, and implemented in weeks. Due to the limitations of Bitcoin script, Lightning takes 60 pages to describe and is still not implemented. It's a revolutionary concept, hobbled by an antiquated platform.
That blogpost is basically describing lightning. Lightning Network has explicitly described instant cross-chain swaps privately, and publicly for many months.