A few things:
1. Lil Boo will not be an icon.
You'll see references, sure, but they ain't going that far.
2. Re: Fear Street and Stranger Things -
Stating the obvious here but Fear Street is not on the same level of ST. We're reaching a point where A+ Headliner IPs are few and far in between. It would do Uni good to try to capitalize on the last ounces of relevance this year with Fear Street since it seems to be a one-and-done series - whereas ST can wait and headline the next event or two.