This is exactly the philosophy that Google Wave had, except they called it an "optimistic" UI - it always assumes that every action will succeed on the server s

This is exactly the philosophy that Google Wave had, except they called it an "optimistic" UI - it always assumes that every action will succeed on the server side. It solved all these problems mentioned and more - for example, it used the operational transform algorithm to merge your changes with those of other users on the same page and update the client state to reflect this asynchronously. It also could continue working without a network connection - it'd just keep queuing your requests, and when you plug in the network again, it'd just start working again, albeit possibly with a big backlog of changes to merge together. These are the kinds of problems you might have to start thinking about if you want to go down this path. Remember that Google Wave died from its own complexity.