Unfortunately, I think it's just a coincidence. The hard drive business is a mix of specialist manufacturers and 800lb gorillas, which is proving unsustainable.
Hitachi and Samsung are global behemoths (actually, their industry profiles are remarkably similar) who won't stop until they dominate this sector. Don't forget that Fujitsu is still around as well, although I wouldn't put them in the same class.
Against that you have three independents: Seagate, Maxtor and Western Digital. Seagate's critical advantage is that it dominates the profitable SCSI market - heck, their products haven't been class leaders for years now, yet they're still most people's first choice for a server. Maxtor has been doomed for some time and I'll bet Seagate wants the extra size to survive against the giants.
WDC may be harder to explain - can the Raptor range be keeping the company afloat? It has the advantage of having no competition, so I wonder what the margins are? On the face of it, Samsung and WDC are not a good fit - their production philosophies are obviously at opposite ends of the spectrum - but Samsung might want to buy WD's enviable retail presence.