I'm not an executive in a film studio.
The way I approach this is; I don't pretend to try to fully understand Hollywood accounting or how studio economics works.
* What I can do is look at box office performance with movies in a science fiction film franchise like Star Trek. I can see their production budgets and their worldwide box office and what films got sequels.
That lets me understand about how much money a Star Trek film (or even an Alien movie) needs to make (compared with its production budget), in order to get a sequel.
- "Star Trek: Insurrection" was a slight flop. Production Budget: $58 million. Double that = $116 million. But the film's box office = $112,587,658.
Still "Insurrection" got a sequel.
- The sequel, "Star Trek:Nemesis" flopped hard. What I'd call a bomb. Production Budget: $60 million. Worldwide box office: $67,312,826.
Barely above 1 x production budget. Imo it lost $millions and that ended Star Trek movies for 7 years.
* Back to "Covenant". It could get up to about 2.5 its production budget from Japan's box office.
Both "Star Trek (2009)" and "Star Trek Into Darkness" made box office that was about 2.5 times their production budgets.
Those Star Trek movies got sequels.
- "AVP" had a Production Budget: of $60 million (Box Office Mojo) to $70 million (Google). Box office: $172,544,654. Using the Google budget = box office about 2.5 x the production budget. (The Box Office Mojo budget = box office 2.86 x the production budget.) And "AVP" got a sequel.
- Conclusion based on this information?
If "Covenant" makes about 2.5 times its production budget (after its Japan release), it could get a sequel.
* As for comparing a Star Trek film with an Alien movie; in several ways "Prometheus" was similar to a sci-if adventure Star Trek film.
There can be an overlap between the two franchises in terms of overall style imo.
For instance "Star Trek First Contact" had horror elements in a sci-if adventure (like "Prometheus"). And "First Contact" made about 3 x its production budget.
I'm not sure, but I think distributors get around a third of box office receipts, and in several cases probably half.
In general, then, one can consider doubling the cost (because of marketing), and then cutting revenues by a third to a half (because they go to distributors), then adding ten percent for the profit margin. In a worst-case scenario:
Production cost: $100m
Marketing cost: $100m
Total cost: $200m
Box office receipts should be $300m to $400m (because $100m to $200m will go to distributors) plus 10 pct profit margin (around $20 million).
Other factors may be considered in decision-making, such as domestic sales, whether or not there are other franchises or projects that may make more money, and so on.
Finally, I think one reason why the Star Trek franchise keeps going is that its revenues do not rely solely on box office receipts but multiple movies and TV shows.
My disagreements with this argument;
1. The claim that box office needs 4 x the production budget to be get a sequel is just a theory.
* We can test the theory of when studios approve sequels by looking at the numbers and seeing when sequels are approved. (From the numbers.com website) http://www.the-numbers.com/movies/franchise/X-Men#tab=summary
- May 26, 2006 X-Men: The Last Stand, production budget: $210,000,000, worldwide box office: $459,359,555, ratio box office/budget = 2.19
- May 1, 2009 X-Men Origins: Wolverine, production budget: $150,000,000, worldwide box office: $374,825,760, ratio box office/budget = 2.49
- Jun 3, 2011 X-Men: First Class, production budget: $160,000,000 worldwide box office: $355,408,30 ratio box office/budget = 2.22
So, that's two franchises (Star Trek & X-Men) where sequels were approved with box office being about 2.5 x the production budget or even less.
I could find more examples.
2. A movie makes money from more than just theater box office. There are disk sales (DVD/Blu-ray), streaming, cable broadcast fees, and with science fiction there are merchandising fees from toys and comics.
** Back to "Covenant"; a sequel could happen if its box office gets to 2.5 the production budget. Why? Because there are multiple movies which got sequels (like Batman Begins, Star Trek, X-Men) where that kind of performance got a sequel.
3. The Alien franchise is considered to be one of the top science fiction movie/TV franchises of all time. http://screenrant.com/greatest-science-fiction-franchises-ever/
The challenge for the Fox studio is to figure out how to release an Alien franchise movie which can get better box office.
Whether the studio goes with a film more like "Prometheus" or "Aliens", there is the potential to make money and because of that, the Alien franchise is not dead.