When the platform changes, the leaders change.

Wordperfect had a virtual monopoly on word processing in big firms that used DOS. Then Windows arrived and the folks at Wordperfect didn't feel the need to hurry in porting themselves to the new platform. They had achieved lock-in after all, and why support Microsoft?

In less than a year, they were toast.

When the game machine platform of choice switches from Sony to xBox to Nintendo, etc., the list of bestelling games change and new companies...