What give you this confidence? I discovered the list when I was trying to figure out why "link:" was no longer working, after existing for more than a decade. In another comment here, TeMPOraL says that "define:" (which is on the list) doesn't seem to be supported any more. If it's not making money for Google, and it's not necessary for their internal activities, I wouldn't want to depend on any of these to work in the future.

The + operator was removed despite being there for a long time.

Also there's a whole bunch of wrong info in the article. The most blatant one is that they claim google by default performs an AND search, which even a cursory use of google will demonstrate is not true.

Most work, but about 1/4 of them don't :(

link was intentionally removed, I think about a year ago, with some messaging to the community. I would guess it was being abused.

By abused you probably meant abused without payment to Google, or abused by people external to Google. People who pay or are Google can continue their abuse.