Thanks for the explanation. I wasn’t aware of the other possibilities and it’s really helpful of you to explain it more precisely - that will definitely be useful in the future 
E.g. having that mesh plugin as a hard dependency rules-out HTML5 and that should be handled well.
I think in my case having a hard dependency would actually make sense, because I wanted to use the plugin to generate terrain geometry, which is crucial, however to have more control I’ll eventually implement my own code based on the CustomMeshComponent as example.
I am also wondering - is it possible for the plugin to be missing? I’m the person who has the local installation of engine and would package the game, so it’s hard to imagine such a situation for me.