The sarcasm was more referring to the fact that Java (and to some extent Flash with Alchemy VM stuff) is already the best solution for cross-platform native sandboxing in the browser.
(If Oracle improves on the updates, that is, and I'm sure they will, they've got a lot on the roadmap for Java.)
This is a neat idea though!
I'd rather trust PNaCl for a portable secure implementation going forward than I would Java Applets experiencing any sort of resurgence.