Wow... this is quite sad news indeed...
I discovered Fractals as early as 1.5 years ago, and really got into them for a while.
So much that the mathematical concepts fueled some ideas for comics that I've got cookin'.
Man... I kind of wanted to hear what he thought about my theory for a Multiverse level 4 Fractal-geometry dominant Universe.
( the idea is that although our own Universe's geometry is fundamentally based on fractal geometry, there are other geometries visible as well, such as simple ones. But what if the laws of nature are changed, so that the fractal geometries become completely dominant? Structures such as atoms then change radically, or cease to exist!)
I also just read that he himself had done some ponderings on multiversal theory... wow.. too late did I find this out.
May his legacy never be forgotten or trivialized. Here's to Benoit Mandelbrot. Your work will always be an inspiration to me.