Scenario 1 is far more likely. Why?
1. CBS will retain all the sets, costumes, props, CGI models, etc. from the films. All they have to do is recast the principles again with unknown, cheaper-priced actors for a TV series. That's exactly what happened with M*A*S*H, and look how that turned out.
2. When the casual audience thinks of Star Trek, they think of Kirk and Spock. They don't think of Picard and Riker. That's kinda why Abrams chose the TOS setting for his movies. CBS wants casual viewers to watch their show, not just the extremely tiny (in comparison) Trek fanbase.
3. What exactly would be the point of creating a nuTNG series? What stories could they tell that they couldn't tell with a nuTOS series? nuTOS seems to be quite futuristic enough without having to add yet another century to the timeline.
4. Not that I think TV producers would ever think logically or realistically, but based on what we've seen in the two films, the 24th century of nuTOS would most likely be completely different than TNG. It's possible that Picard, Riker, Worf, etc. may not even exist by that time.
*EDIT* After re-reading the OP, I realize that this wasn't actually a discussion about whether a new TV series will be based on nuTOS or nuTNG, but rather just a thought experiment about an imaginary nuTNG series from someone who seems to have Abrams issues. My apologies.