Google Wave is, as you probably have heard by now, Google's attempts to redefine email. However, this has no chance of replacing emails anytime soon. And by soon I mean, not in another 5-10 years. Google Wave has no use for normal users. This is mainly because in order to communicate with others, they must also have Google's Wave. This is a huge draw back even if every Gmail users start using Wave. Google Wave needs the ability to have backward compatibility with "current generation" email. Only use case I can think of right now is for collaboration.
Google should really try to pitch the concept of Google Wave - that is to have One-Copy-Threaded-Email (I made that up...) , which stays live in the server and keeps version of all changes. In an essence this is the core of Google Wave. Every other features, like timeline, widgets, and all fancy drag and drops are nothing more then ahs and oohs.
Different type of email protocol isn't something new. Currently we have two standard and most widely used email protocols, - POP and IMAP. So a new protocol, say Wave, won't be something totally absurd. Just like it took quite a while for IMAP to take off, it's okay if Wave takes similar bumps. But until it becomes a standard protocol, Google's Wave has no future.
