The name will surely live on in some offering or other, but the dynasty has already faded.
it would be pretty interesting to see a post-Microsoft tech world, but I can't imagine that happening until a worthy successor dethrones them, rather than simply fading away.
With regards to the primary three product lines: the OS and the office suite, plus the corollary server solutions, Ubuntu + Redhat seem to be pretty effective at stealing former Microsoft clients, particularly governments. Hell, even Amazon's getting in on the act with EC2 sales to the CIA.
That's fairly strong evidence on its own, but in addition the world has shifted away from desktop and Microsoft's strongest position against this is essentially office work requiring a keyboard and XBox/gaming rigs. SteamOS is going to add further challenge to the console space, and encourage development in a cross-platform direction, and we've already seen open and largely interoperable source office solutions proven at scale.
If you had to point at a successor, I believe it's the Linux world in general, but from the consumer's perspective Ubuntu.
Though a Jobs-related counterpoint, Apple was in a pretty rough place at one time, too: http://en.wikipedia.org/wiki/Gil_Amelio#Apple_Computer
I think it's still much too early to count Microsoft out, they've still got a whole lot of runway ahead of them before they run out, and cutting such a huge part of their work force could just buy them even more runway, enough to get their bearings and recover. I think it would be pretty interesting to see a post-Microsoft tech world, but I can't imagine that happening until a worthy successor dethrones them, rather than simply fading away.