The biggest API integration I know of is Splitwise. Their Android app has 500K+ installs and it's probably the same ballpark on iOS, which puts them leagues above a college kid with 2 likes.
Splitwise will continue to work and run. The API is not being shut down, they are simply not authorizing new API applications. The article is wrong and massively misleading.
Because they are owned by Braintree (big payments processor) who is owned by PayPal (who used to be owned by eBay before being spun out to be independent)