How to switch content site to user generated (social) content site

Hi,

We’ve got a fairly established blog network with 1000s of originally written articles - GameFlavor Network. Due to current focus, I would ideally like to supplement the original content with user generated content, if not then a 100% user generated site, but have found this is easier said than done. Technically it’s not an issue, but to switch your site visitors over to a new format can be a challenge.

Would welcome any thoughts on this, especially from anyone who’s gone through a similar transition.

Thanks