[JKT]

I think there are quite a few things that could stand improvement in OmniWeb - autofill and RSS being two of the most obvious. The Workspaces feature, which is currently OmniWeb's trump card for me, could be made even more advanced and tab handling could be improved (that is, have tabs open by their parent rather than at the bottom of the list, return to the last tab used rather than the one immediately above, etc). There are also plenty of other power user features that can be added, and further improvements could be made with respect to integration with the OS and other apps to keep OmniWeb enticing to the user to stay with it.

It is also worth pointing out that even if 3.0 or any future version of Firefox is written to support OS X fully, it is still an app written for three different platforms (both a strength and a weakness) and it will still suffer usability flaws because of its need to fit three very different UI philosophies. Similarly, the extensibility of FF, though one of its greatest strengths is also a huge weakness. Due to the bewildering number of extensions available, trying to find an extension that really carries off the one feature you would like is often very difficult. The current rating system just leads to those extensions that became most popular early on staying most popular because they are the only ones that are easy to find. There could be much better implemented alternatives, but finding them demands an immense amount of time and patience. In the end, what appears to be happening is that there are a core set of extensions rising to the surface that pretty much offer the same features already present in other power browsers such as OmniWeb, Opera and iCab and not much else (sometimes they are better implemented, but just as often they are worse), and these are slowly integrated into Firefox itself. IOW, why not just start with the browsers that have these features built-in by default?

Edit: I should answer your question - will a better Firefox "turn up the heat"? Of course, but I don't think other browsers are going to stand still. I just hope that an improved Firefox takes away even more market share from IE on the PC so that web site owners have to actually think about the way they design their sites instead of catering to the IE crowd to the exclusion of others.