Hi Ziya,
I think if someone forced me to bet my house on where we'll be in say 3-5 years, I'd say we'll have something along the lines of Flex being the most popular solution. I'm not so convinced it's Flex specifically, but something along those lines.
I think the reason for this is that people see that while the typical web applications using AJAX have plenty of pluses, they tend to have a number of minuses too, and a lot of them are addressed by what I'd have to call thin fat clients. There's certainly no denying that a decent Flex app looks a lot better than most AJAX apps for instance, and it also addresses a lot of the underlying complexity in a large AJAX app (concurrency, error handling, etc).
It's interesting... I've spent the last year or so developing a very large, complex AJAX-based app at work, certainly are a far grander scale than anything in either of my books (although there's some cool apps in both!). Early on, we had some good debates about whether we should go with Flex or not, and we sort of have discussions about what we should have done all the time
There are still some concerns with Flex that probably would cause us to make the same decision, but we've certainly learned that the choice isn't an easy one. As well as the project turned out, it certainly wasn't without plenty of days of banging our heads against the wall to make it work, and many of the problems we had to solve wouldn't have even come up with Flex.
As for things like GWT, I may annoy a lot of people, but I've personally got a lot of mixed feelings on it. I personally thing the way ahead is more scripting-type development, although I suspect Javascript is not the final evolution of that. I've never viewed Swing as a good UI technology myself, and extending it to the web never seemed to me a great idea. Now, make no mistake, GWT is extremely cool from a techie's point of view! Very neat in that regard. But, would I want my team developing applications that way? To me, it seems like a step backward frankly.
I do think we're going to at some point see a de facto standard emerge. Maybe it's Flex, maybe it's something else, I don't know. But, I think your observation is correct: I think we're going to see some sort of universal (i.e., most platforms) fat-client-ish runtime that the UI is built with, just calling back to the server to fulfill service requests essentially, because as you pointed it, this is starting to be the trend anyway. I don't really suspect there is going to be any standard pushed through by any standards group (I think they tried that with
JSF and got a lot of backlash for it), I think it'll be something that kind of takes us by surprise and everyone says "yeah, that's it!".
