None of those assertions match the public history: they rejected attempts to monetize Reader, it wasn't getting much (if any) maintenance time, and the decline in demand was in no small part due to Google's decision to kill the most popular product in that space hoping to boost Google+, providing no counterbalance to Facebook's attempt to lock up the syndication market.
Gmail and Maps will not be cancelled because those sell a ton of advertising data. The Google products to worry about are the ones which don't funnel data into their ad system.
The maintenance cost I mentioned refers to the cost of bandwidth and storage capacity required to cache and push content to the clients. No competitors to reader had the resources to offer a comparable product.
The service they pushed to replace reader was not Google+, but Google Now which ended up in the same graveyard in a few years.
On the topic of monetization, this was covered in some of the articles at the time. This isn’t the best one but:
https://gigaom.com/2013/03/13/chris-wetherll-google-reader/
“ Wetherell agreed. “The reader market never went past the experimental phase and none was iterating on the business model,” he said. “Monetization abilities were never tried.”
“There was so much data we had and so much information about the affinity readers had with certain content that we always felt there was monetization opportunity,” he said. Dick Costolo (currently CEO of Twitter), who worked for Google at the time (having sold Google his company, Feedburner), came up with many monetization ideas but they fell on deaf ears.”
http://massless.org/?p=174 goes into more detail about the history and I think in retrospect the subsequent decade really supports his argument that Google leadership is unwilling to try to create new markets rather than enter already proven ones. Trying to barge in on Facebook with an unwanted, un-QAed Google+ only left Facebook stronger and ensured that all subsequent Google products had launch-day questions about cancellation because so many influential people used Reader.
It wasn't really mentioned in the interview but I just remembered that AdSense for feeds was a thing, however it was very poorly received and did little to solve their conundrum.
What criticial feature did Reader have that is not comparable in the competitors? Honest question, when Reader shutdown I imported my data in a competitor service that I use to this day.
Other feed aggregators may have better UX or social integration (IIRC reader have always had an open API available in case you preferred a different client software) but none was or is able to replicate what reader has done for me.
Stadia, on the other hand, has been a product designed to be commercially self-standing. Yet somehow it was never that attractive from the beginning. It makes one wonder if it was simply a "me too" gesture to please shareholders and they simply left it at that.
Now let us make a wager on when gmail and maps will be cancelled...