In other words, just a note at the end of the most recent chapter indicating the likelihood of more to come, or else a "so long and thanks for all the fish.

Yes!! Such a simple thing that would also stop the oft repeated question of when an update is likely.

I've also seen posts where authors have clearly said they have other pressing matters and the next chapter will be a long time coming, then some not very observant reader posts the update nooow! comment. *rolls eyes*