After speed, what's the next challenge for web browsers?

Looking at the current array of web browsers, it seems that all the major players have made dramatic improvements when it comes to speed. Even Internet Explorer 8, which lags far behind the rest of the pack, is not only significantly faster than previous incarnations, but it's also fast enough for speed not to be an issue for most users. With the speed issue solved, what should be next on the browser developer's agenda?

The overall quality of web browsers affect us all, and despite having more (and better) choice of browsers, we're still limited to offerings from a few big players. We're also accessing the web using a broad range of devices, and the Internet experience varies greatly depending on what device you are using.

Than there is the ever-increasing threat from hackers and malware. Browsers are most user's first line of defense from people trying to take over their systems or steal their cash or identities.

With that in mind, this is my personal wish-list for browsers:

• Security: I'm going to put security right at the top of the list because this is one feature that would benefit everyone. While browsers certainly have security-enhancing features that were unknown a few years ago, I still think that there's a long way to go. I think that ultimately all browsers will be 100% sandboxed from the OS. It should also be much harder to run code from the browser.
• Performance: I still think that most browsers are bloated. I find myself using Google's Chrome more and more simply because I like dealing with a browser that's fast to load up and doesn't start to feel slow once I have a handful of tabs open.
• Features: I felt for a while that browser developers had lost sight of what a browser was. Ultimately we want a web browser to display web pages. It should also make it easy to find what we are looking for and even easier to back to what we've been looking at. Beyond basic features I think that careful thought needs to be given to what features are shoe-horned into the browser. The Firefox model of relying on add-ons is a good one but I feel that the release of new versions breaks too many add-ons. As such I find it hard to come to rely on any one add-on.
• Cross-platform support: What really annoys me about the current state of browsing is how I can't get any level of standardization between desktop browsing and mobile device browsing. What I'd like is a situation where I can have the same basic browser on my desktop, notebook, netbook and mobile device. I'd also like a quick, hassle-free way to sync my bookmarks. I know that this is all possible to some degree already, but it's far from perfect.

Thoughts?