I'd actually expect Pentax system to live longer than some other, better known brands unless something really serious happens. Because of their devotion to optics and photography.
It seems that there is some photography hype happening nowdays by the introduction of digital media and expansion of internet. The thing hasn't stabilized yet. And when it does i believe some hybrid media solution will crystallize in consumer segment (as 35mm photography did some years after numerous photography techniques appeared or got replaced in the early years - something handy, giving acceptable quality and flexibility to most everyday users in usual situations). This will force the big companies reorganize their business. Some might just cut their photography line completely, others transform it into some ubercamcorderphones.
But Pentax is already adapted to lower volumes and has its market where people are interested exactly in photography. Many of other band buyers are one time gadget geeks.
They are affected by media hype and will continue their road to new product types and features without continuing photography as their hobby or profession. Thus they will not be more or less exclusively interested in photography equipment.
You can already see a person change brand several times a year, then sell all their photo equipment, and start buying video stuff or get into computer games/overclocking, bikes etc (I'm not saying you cannot do this all at once
).
Just a thought. Correct me if i've mistaken.