Cross-training is an important aspect of business operations, and a good starting place for a paper would be to do some research. There are business journals that discuss this topic, and you could visit local businesses to find out what kinds of cross-training occurs by interviewing people from human resources departments or managers.

You should ask yourself what the point of cross-training is.  Who benefits?  Is it good for employers? Is it good for employees?  Does it increase profits?  You might want to create a hypothetical scenario to discuss these questions and answer them? 

Are there companies that cannot benefit from cross-training? For example, on an assembly line, is it useful for employees to know how to work on different kinds of parts? What about a restaurant?  Should the host know how to wait on tables, or should the waitstaff know how to host?  What about an insurance company that sells many products?  Should all the sales staff know how to sell all products, or is there anything to be gained from having specialty salespeople? 

I suspect you will find that different kinds of industries lend or  do not lend themselves to cross-training, and that might make an interesting focus for a paper.