With the arrival of new generation browsers and HTML 5 (which includes enhanced graphics and multimedia capabilities) people might start thinking that it is a big threat for browser plugins like Flash and thus for developers who live from those technologies. I will try to explain why it is not as it might look like.
First of all let's talk about Chrome, the choice by Google is clear, let's create a new browser using a mature and popular HTML rendering, so without reinventing the wheel and without creating hassles to UI developers, but focusing on the user experience. At the end Google got popular because of that, their search engine was the favorite from the users because their website and their queries' results were the fastest to load and the results were the most related, because better performance means better user experience. With Chrome they did some geek stuff behind, that's true, but from a user perspective you can simply say that you will be able to perform javascript faster than the others, you will have less memory problems (especially useful for large javascript applications) and you will have some interesting features like dynamic home and incognito browsing.
So if javascript and memory management will improve, and if HTML 5 will bring multimedia and enhanced graphic, why would you still develop RIA plugin based applications?
1) Expressiveness: Plugins will always be ahead in terms of features, this is because they are not restricted to standards so they don't have to wait anybody before implementing new functionalities. At the moment, for instance, with Flash you have 3D, access to bytes (there are already ftp and MySQL libraries), usage of webcams, last, but not least, good integration with tools creative people use. The web is not only text or RSS and if you want to compete with others, is better you try to differentiate yourself using at its best the newest feature available.
2) Performances: You can differentiate yourself also providing the most reactive
experience and if you use Flash with its optimized binary
communications and its fastest rendering engine, you are definitely at a good point.
3) Development environment: Using Object Oriented and strongly typed languages like ActionScript 3.0, Java or C# allows you to write more reusable code and to architect better large scale applications. Pre-compiling also helps your IDE to better support your writing. For this reason Google uses their web toolkit for their JavaScript based applications (where you basically write the application in pure Java), and other solutions like Objective-J and Script# are getting more popular. It's clear that new browsers will permit you to run downgraded RIA applications compare to the plugin based ones, but how these will be written? I'm sure more similar to how plugin based, and desktop applications in general, are, so no worries if you are a Flash developer.
4) No cross-browser/platform issues: The plugin vendor is responsible for making your application perform at the same way on different browsers and platforms. And most of Adobe clients (the developers who buy theirs IDEs) choose Flash to not to have to deal with those issues. For this reason when asked about Chrome, Adobe said that they are happy that there is a new browser in the market because of their nature of being cross-browser/platform. In the case of Chrome, since it is based on WebKit, doesn't seem a big advantage but, in general, it is clear that harder is the war across browsers and platforms, better it is for Adobe and I am sure Microsoft won't get so much along with Mozilla, Google or Apple.
The bigger threat for browser plugins I reckon is instead mobile browsers. In fact it might be very challenging to provide rich UI experiences on so many, very different and not powerful devices. As Adobe admits, in the future millions of people will have access for the first time to the Internet from a mobile skipping completely the PC step and mobile users will be the first target for websites, so web designers will have to design first for mobile and then eventually for PC. Interestingly enough we are seeing native mobile applications that are basically micro-websites, so maybe the GUI will get simpler but it will be customized based on the device you are using and taking advantage of its features. It is true that Adobe hasn't so much control on the browsers and platforms, but it has monopoly on the content generated by designers, so until that won't change I don't think Adobe will have many problems on being supported by browsers and platforms companies, and Flash plugin will stay the favorite.
To know about the future of Photoshop, After Effects and Flash IDE, stay tuned!