I argue this is both true and not true in stark ways with Google. Just look at Google Groups listserv, it's been running forever and arguably mosts used neighborhood listservs globally and has been very stable.. all largely for free. On the other hand, new experiments get chopped very quickly at Google. So, it's more like if the service can survive 2 years, then Google generally keeps it around*.

* unless it gets merged dozens of times into other similar projects.

It doesn’t matter to me that some of their products have longevity. I don’t know which they will keep and which they will discontinue and there are many vendors out there who have a better track record.