I cant’ imagine Disney releasing an R rated movie, though I’d welcome it. That said, scary doesn’t have to be rated R. Jaws scared the **** out of me and it was rated PG. I think Poltergeist was also rated PG and I think it was fairly scary (and had kids in it as I recall). It may not be scary. It may not even be good, but I’m going to give Feige and company the benefit of the doubt, because I don’ think there’s even a franchise before that has been as good as the MCU (and AFAIK, I’ve only owned one or 2 comics in my life). Most of the time sequels are ****, but Iron Man aside, it seems like the sequels have been good (Age of Ultron, however, wasn’t as good as Avengers).
Until proven otherwise, I assume things will be good on this phase as well. I only wish they’d had someone at lucasfilm insisting that the sequels be mapped out in advance, rather than being made up as they went along.