No competent business leader would kill the cash cow in order to sow seed that may or may not bear fruit. Like IBM and Borland, Corel is making a lot of noise in the Linux space because Linux is the new emerging market with the greatest growth potential. Whoever stakes their claim first gets to set the pace for the late arrivals. That's an exciting place to play, but the meat of the business is still Windows, and will continue to be so for many years. That was the long answer.
Opportunity starts at the base of the growth curve.
That's how you get triple digit return on investment and marketshare. Remember that development tools have to venture ahead of applications by 18 months or more. You won't have a lot of really good applications on a particular platform until you have several really good sets of tools to choose from. Certainly, it's a little early yet to commit resources to developing end-user desktop applications for Linux. Linux has yet to really crack into the end-user desktop OS space.