Fix the fucking bugs you introduced in 3.5 and then we'll talk.
Obviously I can't speak for everyone, but most people don't want glossy bloody buttons. They want a simple, stable, low footprint browser that can be trusted not to eat more RAM than most video games.
At the moment my Firefox is using 340mb of RAM.
Visual Studio 2008 with a BIG ASP.NET project and a class diagram open is using 185mb.
This should be totally unacceptable. 5 years ago we had browsers that operated better than this, and before you say it, no, it's not because the Web has evolved; Geko itself is an compliant and lightweight rendering engine, all the problems are with the UI.
In my opinion Firefox needs shooting. It should be totally rewritten, this time with performance in mind.
It is no coincidence that large chunks of the laptop/netbook market are now moving toward cheaper, lower spec machines.
With Moore's law in trouble, people know it's not about raw power anymore, it's about targetted performance (as in, buy what you need, not want), portability and ease of use.
I'm not going to get into a rant (today) about the general sloppyness that has crept into software development, but it's a trend that WILL reverse, and if the key players don't fill the opening gaps, others will.