Take the concept of the insanity videos that don't require any any weights, but instead of replaying all the same moves all the time you can do the classes live at a specific time, or a prerecorded session that was posted earlier. You will not get bored of the classes because the music changes, you can pick from different instructors, and there can be different levels of difficulties in the classes. Along with this would be a chat room so that you can interact with any one else who is also doing the classes. You can help support each other in a growing community where you can post up pictures of yourself to show the results that your getting from these workouts. You can also seek advice from people if you have certain injuries and want to replace certain workout moves with others. Of course the website would include a diet section where people can again comment on whats working for them and giving their own healthy recipes and eating routines.
This of course would not work for everyone but for people who are intimidated by a gym, or feel like they want to learn about working out before they go to an actual gym could come together. The best part is you can do this at the comfort of your own home. The cost would be small because the personal trainers hosting don't need to a large room to host the class since its students will be at home, and there really wont be a limit to how many people can be joining in live.
In order for something like this to work it would need to be launched by a reputable company like beach body since they have multiple work out at home videos which have been successful under their belt. They can use the faces of Shawn T or Tony Horton who are well known faces to started up, and then ad more personal trainers as needed to ad more classes. The most important thing though is creating a sense of community. The more people feel connected with each other in supporting each other and wanted to post up pictures of their success, the more likely they are to return.