Quoting that post's quote of Steve Jobs' 2005 Stanford commencement address (worth watching, if you haven't),
Death is very likely the single best invention of Life. It is Life’s change agent. It clears out the old to make way for the new. Right now the new is you, but someday not too long from now, you will gradually become the old and be cleared away.
This very strongly applies to web browsers, and as it turns out, the best thing a browser version can do (besides getting things right in the first place) is dying even more quickly than it came. I wonder if this enlightened insight might have sprung with Mozilla, if only Firefox could have kept its inaugural name, Phoenix, which it now fully embodies, but at least now, this gift has finally been given to web developers:
You need not bother writing applications (or perfecting layouts) to high-fidelity for old browsers, for their time is short and their better ancestors replace them quickly.
Assuming your deployment domain is web pages. As browser add-ons go, if you still maintain one of the old style XPI design your work burden has shot through the roof instead, unless you have near zero UI footprint, happen to only need and use APIs that time proves to remain stable and host it on addons.mozilla.org, where they bump its maxVersion every few weeks for you when it still seems to work. Failing either, you have to manually update and test it seven times per year. In Chrome, this has premeditatedly been addressed by not promiscuously offering any APIs it can't support in the long run, at the cost of limiting how much add-ons can do. Firefox, in this regard, remains the only browser where add-on authors can innovate 100% of the browser, and in this regard it has filled an important need in the browser eco-system (and still does). It is both its greatest feature and its greatest burden. Hopefully this will be mitigated to some extent with Jetpack and the new add-on builder.
Returning to the paramount topic of graceful, benevolent, rapid-evolution-supportive death, Microsoft's IE does not yet get it. Like a third world nation befallen by sudden prosperity, it has doubled its reproduction rate while keeping its mortality rate constant. As noted in mentioned posts, this does not bring just better browsers faster, it brings over-population, and makes web development unsustainable. Or, as Paul Irish put it in the first post: it pollutes the browser market.
In this respect, the conditional comments and many "backwards compatibility simulation" modes IE bring you are not mainly tools helping web developers make sites work on Internet Explorer, but a huge extra burden of work forced onto web developers, to cope with IE's broken release process. This is Microsoft's job, not ours, and we should be outraged with them for forcing it on us.
It is not the rotting corpses of IE6, IE7, IE8 or IE9 that all need to die to give space to IE10, which still smells fresh, it is a broken release process that needs to get addressed and brought up to date with best browser practices of the decade. It is the reinvention of sudden death, not just the gift of new life, that must come to Redmond, too. I applaud the IE team for making it their business to get up to speed with the web's evolution, but it's less the whats than the hows that are important to get right now. SVG is great, but sort out the release process before taking on, say, webGL. It can wait. Fixing the world's hard problems like over-population is harder than running after the latest ooo-shiny! - but the alternative is systemic collapse.
For a browser, it is better to live a great but short life and go out with a boom, than it is to burden its extended family with a never-ending old age in an insufferable early-set rigor mortis. However you feel about Steve Jobs he lived and died in this way, never holding back, never growing stale of mind nor action, and the world was better off for it.