Potty training is ultimately a process that the child must control, or else he's not trained. A number of factors are needed for potty training to succeed: the child must be able to notice and recognize the urge before it happens, he must have adequate sphincter control and the ability to hold it long enough to get to the potty, he must understand the point of training, and he must want to be trained. It sounds like at least one or two of these is still missing for your son. Sometimes boys don't really get there until they are 4 or older, no matter how badly parents wish otherwise.
You probably know that night training is a whole separate step for many children, and can lag a year (or several) behind day training. It's not too unusual for third or fourth graders to need diapers at night, and for a few unfortunate kids, they reach adolescence before they stop bedwetting. Their sleep is too heavy for the full-bladder signal to get through, and/or the sphincter isn't strong enough to hold a full bladder, and the chemicals that slow down urine production at night are not produced in adequate amounts. This is more common in boys. They really are not doing this on purpose, and many of them become discouraged and ashamed that they're not able to stay dry through the night.
Sometimes rewards work in the short run if only motivation is lacking. But that introduces the very real possibility that the child will perform only for escalating rewards/bribes over time, and that can become a mistake that you will seriously regret someday.
So, what I would suggest is that, as hard as this will be, you drop your expectations, tell your son you are proud of how well he's growing up, and express your confidence that he will use the potty when he's ready – when he notices that taking a few minutes to go to the bathroom will be easier for him than getting changed. And then do it. Just stop hinting, fussing, reminding, nagging, demanding, bribing, acting anxious or annoyed, or anything that you MIGHT currently be doing around the topic of potty training.
Kids WANT to make this developmental step when they're ready, just as they want to walk and talk when they're ready. Your son will probably need some "space" to work it through for himself. He may need a few more weeks or months.
Meanwhile, you can continue to make all your messages about using the bathroom as positive as possible. That can include modeling how easy/quick it is for you, Daddy and big brother, reading potty books or watching potty videos, having his toys/stuffed animals role-play pottying, and in general making a game of it. With my grandson, once he could do it but didn't want to take the time, I would go into the bathroom and begin noisily ejecting all the dinosaurs that were crowding the room and sitting all over the toilet seat. My grandson couldn't resist that game, and would come in and help me wrestle the beasts, and claim his spot on the toilet.
I think that your son will probably do best if you just wait until he's ready to start this new adventure. Here's a most excellent website that gives a few variations on "readiness" checklists, plus tips on various training strategies, the best ages to start them, and the advantages and disadvantages of each approach: http://www.parentingscience.com/potty-training-tips.html.