Just because a thing can be franchised indefinitely - guys comedically trap ghosts is vague enough that you could do it forever - doesn't mean you should. We used to understand this on a cultural level, that sometimes a thing is really good and that thing being really good is quite enough. We don't need to go back and keep redoing that thing until we suck the wonder, the joy and the magic out of it. We can leave that thing with dignity, revisiting it over time. You can never see the same sunset twice, so why stand in the same place and keep trying to will it back? GO SEE NEW SUNSETS.
The problem, of course, is that it's not about need; it's about greed. I have yet to see a single instance of a franchise being prolonged past its sell-by date because there was some genuinely interesting new wrinkle to be teased out of it.
One thing Devin hits on about Ghostbusters that is easy to forget is how much of a lightning-in-a-bottle project it was. You don't remake those things. You don't repeat them. You learn what you can from them about how to make an original and creative work, and then move on.
I've gone off before about how I won't make sequels to any of my work, and this is exactly why. I want people to crave new sunsets. I don't want people to read something and then assume that the best follow-up to it is something else exactly like it; I want them to crave something else that has the same degree of newness. But again, it's the idea of the new and the inventive and the original that we find more appealing than the actual new, inventive, original thing itself (thank you, Dale Peck), in big part because the actual new thing tends to be so unpredictable and difficult.
The only answer I have is to stick to one's guns. Don't feed the beast. Don't write five books when you know there's only one perfectly good one to be written. Give yourself the freedom to bottle a little more lightning.
You would think that people would be inclined to see new sunsets, but everything I've seen indicates that they would rather just rerun the same one a hundred times and pretend that constitutes a hundred new ones.