You are making a false assumption. I personally use the FeedBurner API to keep track of feed subscribers, for example, and it was deprecated yesterday.

Yes, and it is deprecated, not shutdown: "we have no current plans to remove existing functionality".

Fair point, but isn’t that basically what deprecation is? A communication that something will likely stop working at some point?

Yes, so you may have to spend some of that money you have not been paying Google for Feedburner, and use it to build or buy a replacement.

Not always, it might also mean they moved it into maintenance mode.

....and you still have 3 years to use it! (granted no more development will be done on the API.) So over the next three years which is like an eon in web years you can look for an alternative. Frankly Goolge might even bring out an alternative.

Eh, don’t forget that migrating users from one feed to another would be a huge pain in the ass.