It seems like markets and investors have been accustomed to the huge, meteoric rises of a small handful of star companies, forgetting perhaps that plenty of businesses don't need to become household names overnight to succeed.
One could write a similar article for Microsoft, really. I think they screwed the pooch with Windows 8 and Surface. They tried to protect both the Windows and Office monopolies simultaneously in the face of radical change, and lost both.
IBM has been the biggest player in enterprise IT since it was done with typewriters and adding machines. For them to become irrelevant, even if it takes a decade, is a huge deal.
Ask WordPerfect.
By all measures, IBM != dead (for any predictable future period).
You have to call the right decade, though. :) The startup community started declaring Microsoft on its death bed in the late 1990s...
(You might be conflating the startup community with the open source community of the late nineties, members of which did say that Linux was to "soon" overtake Windows in the desktop).
Considering the large overlap between those two communities, I'm not sure it's an unwarranted conflation. The first tech boom included a bunch of Linux-oriented startups and IPOs, whose successful pitch to VCs involved essentially, "Microsoft is on its way out".
The majority in the late nineties were web startups -- for this new fangled "web" thing. Think amazon, pets.com, etc.
Could we not have said the same thing about RIM in 2009?
By this argument, we can safely say "X is dead, since RIM dies in < 5 years.". Substitute X with any company you can think of. This is obviously wrong, so your argument does not stand.