While the amount of user switching from Windows computers to Apple computers is likely higher than those doing the opposite, there are still numerous reasons for users to switch to Windows machines over Apple ones. Users seeking a more open and customizable experience, hardcore gamers, and numerous others have ample reason to switch.
Yes, I think if the product is good then anyone would change. If the company windows has something apple does not then they will move. I think people care about quality more than anything else in there life. Apple needs to change if they fear competition among other companies. You have to evolve with your audience.
Yes i do think Apple users would change to Windows and vice versa. They are both excellent products to use. I use both. I use an Apple IPhone and love it. I also have owned and used a Windows computer for as long as I have owned a computer. They are both great companies.
Considering the current state of Windows and Apple machines and their performances, I do not believe an Apple user would ever change to a windows machine. My opinion may be biased here, as I am an avid user of iPhone, MacBook, and iPad. I do not see, anywhere in the near future, the possibility of ditching the iOS and Mac OS platforms for Windows. Apple devices have remarkably better durability and performance than Windows machines which is why their higher price tags are completely justified.