As it turns out there is going to be a limit to how many courses you will be able to share in Super Mario Maker when it arrives later this year. Super Mario Maker will feature a series of series of limitations that Nintendo has put in place when it comes to what players will be able to do when it comes to stages created and shared.
This was all revealed in a screenshot from Super Mario Maker you can see above. It appears the initial limit in levels you can upload will be ten, though you will be able to do more if the community, essentially other players, enjoy them and your levels become highly rated. This will in turn earn you a badge, which will provide you the ability to upload an additional ten levels. Based simply on the above screenshot though, it appears a total of ten medals can be earned allowing a maximum of one hundred levels to be uploaded.
So it appears the secret in Super Mario Maker is to make good levels, so you can make more. Hopefully people will like my Super Mario World inspired Yoshi suicide level that I plan on making.