i haven't been following this, but the amount of time they've spent hyping a single hero makes me question how much content we're actually going to be getting long-term.
This is a weird comment. First, you admit that you haven't been following the subject, and then you proceed to make an unfounded conjecture which assumes knowledge on the subject.
Blizzard hasn't really spent much time at all hyping Sombra or any other heroes. Fans are doing that on their own. Blizzard only has a silly ARG running for Sombra because they thought it would be cool to have a mysterious character like this "interact" with fans before "revealing" herself. It's unique to Sombra. The amount of actual effort going into teasing the character is minuscule.
So far they have released one hero, one map, one minigame, and hundreds of new cosmetic items. None of these were teased for any period of time. They were all released at the same time they were announced. All of these were also released after the first initial Sombra tease. Sombra being an ongoing tease is stupid, but that's just how AGRs are. It is not an indication of anything else.