The budget spent so far is around $125 million; with reshoots the film is expected to cost $200 million. There's no way that a major studio like Paramount would cancel a tentpole release like this so deep into production.
I assume the HBO comment was a joke. Of course, there's no way something this expensive would forgo foreign and domestic theatrical box office where it might recoup its budget. (And if someone did make such a boneheaded decision, the movie would go to Showtime, not HBO, since Paramount is the studio here).