There's many company-intern intranet applications still in use out there, which rely on old IE features like ActiveX and whatnot. Afaik, older versions of .NET came with features that required IE.
Also Asia always was and to my knowledge still is using a lot of IE - not sure about the reason why.
A little history lesson:
* Netscape wanted to dominate the web, gain a monopoly and gain full control.
* IE came late to the party - long after Netscape was already established
* MS invested a *ton* of resources to catch up, rapid development pace, quick updates, constantly new features and improvements
* MS too wanted dominance and full control of the web
* MS gained marked share through "dirty tricks" leveraging their OS dominance
* MS got repeatedly sued for unfair competition, paid large sums, paid lip-service to the courts but never truly changed their strategy
* that hurt Netscape but didn't kill it
* what killed off Netscape was their own doing: a costly code rewrite, that took way to much time and delivered subpar results
* Microsoft won, they had what they wanted: full control of the web, and the power to shape it however they saw fit
* they did nothing. they just stuck with IE6, no new features or improvements for years, even bugfixes and security fixes became really slow. all momentum was lost.
* Firefox rose from the ashes of Netscape - MS still did nothing.
* Firefox gained significant market share - that finally kicked MS into gear
* MS re-started updating and improving IE - but they were technologically behind and had to play catch-up again
* Chrome entered the ring and boosted the pace of development
* IE never fully caught up
* Chrome gained full dominance of the market - but unlike IE did not slow down development
* MS tried all their dirty tricks again - but they still continued to loose market share
* they rebranded IE to Edge (still using the same render engine, but dropping backwards compatibility)
* they dropped their own render engine, and switched to using webkit
* despite even more dirty tricks, no breakthrough success in terms of market share
I believe the fading of IE pretty much started with Microsoft resting on their (un-earned) laurels, after Netscape died. And yes, that's even before IE peaked - while they still had upwards momentum.