Agatha Christie wrote over two dozen novels that starred Hercule Poirot, and so the possibility that we could see several of them turned into films certainly has to be considered under the circumstances.
If Death on the Nile succeeds as well as Murder on the Orient Express did, we could very well see more movies where these came from.
While most of the time when we think of major film franchises they are limited to major blockbusters, but it’s possible we could be seeing a new film franchise being born here that won’t require massive special effects or costumed heroes.