I promise they will!!!! I have a 10 and 7 year old - and they are amazing sleepers. They transitioned into their own beds around 2.5 years old, and sleep through the night every night. As a matter of fact, my kids ASK to go to be every night by 8pm. I have never once had an issue with them not wanting to sleep - because they loved sleep (in my bed : ) as babies and toddlers and felt safe and secure and those feelings followed them into their own bedrooms when the time was right.

Our 5 year old daughter is still in our room, but we transitioned her to a mattress on the floor next to our bed instead of in our bed. This gives her the security she needs and gives us a little more space in the bed!

They do leave! If you are still experiencing trouble, try small transitions. Like Alex-Dad said, the mattress on the floor next to the bed is a great idea. Then maybe reverse it, put the boys in their beds and you sleep on a mattress in their room on the floor. Slow transitions help! Eventually they will adjust!

My kids wouldn't sleep in their own beds until we let them pick out larger (full or queen) mattresses and their own sheets (favorite characters, etc). Then we told them they could come snuggle with us as soon as the sun came up. It worked!

I've also heard that quality time with your child before he or she goes to sleep will help the child feel like they won't be missing anything during the night. A friend of mine was having trouble with her now five year old but she found that bedtime stories, a calming environment and a slow-paced goodnight made her son feel more comfortable going to sleep in his own room.

I agree with SuperDuperMom, my wife and I just tried to get a bedtime routine going that they can get comfortable with.  You gotta teach them that they can't always come into your bed whenever they need to.  If this means reading a story, singing a song, doing the night time dance (dont' ask!), then they can start to associate that with wanting to be in their bed.  Also, you want to make their bed look as inviting as possible.  When I was a kid, I had 20 stuffed animals on the bed to make it feel like every night was a slumber party.  Maybe something like that would help?