Boys really don't care what their beds look like. From the time they turn 8 years old, they become more concerned with gadgets, friends, big boy toys, and just being cool. By this time, you should have gotten the cutesy baby boy blue style of boys beddings, and you are now ready for more "grown up" boys bedding.
Of course, there are some boys who prefer to be nostalgic and keep their old sheets and bedding as a link to what is comforting and familiar. In cases like these, you need to let them keep their memories intact even if it means letting the old bedding in the room. What you can do is slowly make the changes starting with the new blankets, then a nicer bed skirt, before moving on to the sheets and pillowcases.
Black Baby Bed
If you want to make the transition from toddler to young man, boys bedding will also need to be upgraded. You will move from cartoon characters or rocket ships to more abstract or "idol" type of sheets. For example, if your son likes a certain band, you can get something that relates to that. The change is actually more traumatic for parents, especially the mother, than it is for the young man.
When it comes to choosing the design, color, and artwork on a boys bedding, you don't have to stick to the color blue. Although blue is the most common color, and one used all the time for boys accessories and items, you can actually consider other colors like black, brown, red, tan, green, or white. If you have a situation where there is sharing of rooms, then consider the taste of each person who uses the room.
You could even designate specific corners of the room as individual spaces, and it will be evident by the change in bedding colors and design. You won't even have to use dividers or put up fake walls.
If your boys is old enough to help in making the decision, ask him. You might be pleasantly surprised by their input. However, even if you do not appreciate their ideas, do not knock them down without considering them seriously. After all, this will be their space, and one that their friends will see when they visit. Thus, allowing them to be proud of their "space" will help them with their self-esteem. Just make sure to still have some degree of control.