I think you are trying to make the point that there is the ethical argument to consider the impact of a decision if your project has grown large enough that there is major dependence on it.
I do agree there is an ethical obligation to make some effort to consider impacts like that, and make an attempt to inform users of your intent, but that's all it is. No one is obligated to be ethical, either, when it comes to a personal project with volunteered time and effort.
I think the argument of obligation becomes a stronger if your project has taken on a lot of contributions from other parties. And yet, those contributors must acknowledge that they are willingly doing so with no promises except the posted license terms.
I do agree there is an ethical obligation to make some effort to consider impacts like that, and make an attempt to inform users of your intent, but that's all it is. No one is obligated to be ethical, either, when it comes to a personal project with volunteered time and effort.
I think the argument of obligation becomes a stronger if your project has taken on a lot of contributions from other parties. And yet, those contributors must acknowledge that they are willingly doing so with no promises except the posted license terms.