I'm not so sure that IE is that important for forward-looking development. It has a rapidly diminishing marketshare on the desktop, and that trend looks likely to continue. Firefox has a staggering amount of momentum right now, and Safari is gaining as well.
Moreover, IE has no presence on the iPhone, Palm, Symbian, or Android. That's tens of millions of new devices that Microsoft has zero leverage over. Unless they pull a real miracle out of their hat with the upcoming Windows Mobile, Microsoft is going to be a bit player in the uber-important mobile market for the foreseeable future.
IE will likely linger for a long time, but at this point it's looking a lot like Novell NetWare ten years ago: still big, but not driving the market.
I suspect IE's market share will never go below X% (where X is high enough to be significant) as long as it's the only browser bundled with Windows and Windows itself has most of the desktop market.
As long as that's the case, businesses will have to support it. IE may not be driving the market, but can still hold it back.
It'll only hold you back so long as you're wanting to capture 100% of the potential market. Obviously Facebook and Google can't afford to give up any potential customers, but a lot of businesses can.
How many websites have you seen that demand IE? That was acceptable because IE was a majority, and offered certain features like ActiveX. Once IE becomes a minority, isn't it reasonable to demand that users of your HTML 5 application use something else?
My claim is that IE's market share will not become insignificant for a long time. You seem to have read it as "IE will retain nonzero share for a long time".
"IE will likely linger for a long time, but at this point it's looking a lot like Novell NetWare ten years ago: still big, but not driving the market."
Sounds like you forget to include the 100 million enterprise desktops locked down to ie by their employers.
Actually, that's what makes them like NetWare. If IE fails to keep up, those dominos will eventually fall, albeit slowly.
There's still huge NetWare shops (like the California Energy Commission), but they're ever-so-slowly dropping away. Install base doesn't matter. Growth rates do.
Moreover, IE has no presence on the iPhone, Palm, Symbian, or Android. That's tens of millions of new devices that Microsoft has zero leverage over. Unless they pull a real miracle out of their hat with the upcoming Windows Mobile, Microsoft is going to be a bit player in the uber-important mobile market for the foreseeable future.
IE will likely linger for a long time, but at this point it's looking a lot like Novell NetWare ten years ago: still big, but not driving the market.