Fallout 4 will be next. Without a shadow of a doubt. New Vegas was a spin-off developed by Obsidian, and as such doesn't effect the simple pattern of Elder Scrolls>Fallout>Elderscrolls and so forth. Plus, Elder Scrolls Online is coming out later this year. It would be incredibly stupid on their part to be releasing an Elder Scrolls game on top of the MMO people will be playing.
Before anyone says anything, yes I know Elder Scrolls Online isn't developed by Bethesda. The point is, it would be a bad idea from a business standpoint to over saturate the consumers with elder scrolls. Better to let the MMO stand alone, sink or swim for a few years. After 2 years or so people will be tired of it most likely, and will be more welcoming to a return to the single player version of Elder Scrolls.
Edited by Kraeten, 18 May 2013 - 12:15 AM.