So in the store, it says Rise of the Goblins was 5 scenarios long. Is that it? Are we only getting 1 AD for the goblins?

Maybe. Maybe we will get ad 2. There is not exact info about this matter.

The only info is

http://forums.obsidian.net/blog/8/entry-204-pathfinder-adventures-rise-of-the-goblins/

 

After Goblins we will get mini Valeros adventure.

 

So mini scenarios is what to Expect in the future based on above information.

To make it easy on anyone who stops by, here's the relevant info cut-n-pasted from the above link:
 

The Future

The next content after our goblin deck is still being designed (and possibly named something else) but it is currently being called a Side Quest and is going to be character specific. Meaning you can do them with different sized parties but it requires the character of focus to be in the party.
While this is subject to change, we plan on opening up with a series of five scenarios that explore some events that befall Valeros (he does have an interesting backstory) and culminate in unique rewards and a new character added to the roster.

Who that character is has been currently narrowed down to one of two choices but they will be coming from the Fighter Class Deck and it isn't another version of Valeros, so that's your hint.