This product is how Alphabet itself gets all its business done, so that seems unlikely. Could it be replaced with something similar in the longer term future, like the Hangouts -> Meet transition? Sure. But that transition was pretty easy since it was still the same accounts on both ends, which would be true of any future Meet transition as well.
I think what OP specifically meant is that it's a first they actually charge for a product like this, so your predicted outcome is less likely.
The problem with google killing and making new "same" products is not monetization, but internal power struggles, where noone wants to be just a maintainer, but every boss wants to be the one to bring a new product out, even if it essentially does the same thing as before.
It's at least partly about monetisation. Nobody is worried about Google discontinuing their search or ad businesses.
Diane is basically running the business now and the vision is fairly clear at his point. I doubt that will be happening for meet. Google is organizing itself around key verticals (websearch, cloud, media, office/collab, and devices). Meet is a key feature for their office suite.