Nike is not stupid. Tennis is shrinking and the profit potential just isnt there anymore. In this economy they are going to market to the upper class as they are the ones who can afford to drop big money on nike gear.
Is it really bad that Nike is pulling back from tennis? I dont think so. I like different brands in the sport. I see Diadora is marketing shoes again. Thats nice. Maybe some new companies will enter the market and some of the older ones will come back.
Nike probably wont push hard into tennis again until a new super crop of American players comes into play ala Agassi, Sampras, Courier etc. Isner and Harrison are not really marketable like those players were.
honestly though I have not been a big fan of Nike in years. I liked there stuff in the mid to late 90s. After that....meh. They used to make pretty classy tennis clothes that looked great and felt great. I wouldnt shell out the money for it but it was nice stuff.