Think about it this way. Microsoft is driving more and more users away from Windows.
People are willing to re-learn another platform and abandon your product in order to avoid dealing with Microsoft. That number is growing, not shrinking. The question is how much of that market share do you want to lose? If I relearn another platform then 2 years later Adobe enters the Linux game, I'm not coming back. You've had the opportunity for years.
Think about it this way. Microsoft is driving more and more users away from Windows.
People are willing to re-learn another platform and abandon your product in order to avoid dealing with Microsoft. That number is growing, not shrinking. The question is how much of that market share do you want to lose? If I relearn another platform then 2 years later Adobe enters the Linux game, I'm not coming back. You've had the opportunity for years.