Because?
Because featured snippets will be the only answer from these new gadgets, and so other posts will lose their current value in a world where people converse with their devices.
Look at the progressive increase in voice searches list of phone number in philippines since 2013 (brown – Navigate Home) to draw your own conclusions:
And what does Google respond when a voice query is made?
Responds with the voice of the assistant that “reads” what is inside the featured snippet.
Just like that.
What if we do it by voice and in a natural way?
We probably approach our cell phone—or our smart speaker—and say: Ok, Google, what do I need to do to work in the United States?
Google responds with the text inside the featured snippet.
Google Featured Snippet
You can see a smooth continuity in the response.
Let's analyze it.
What to do to work in the United States? To be able to work in the United States, you must….
We observe that it simulates a conversation between human and machine with some fluidity:
What to do for (…)? And Google responds with “For (…)”.
If Google's answer were: “A resident card…” there would be a feeling of a canned response; however, answering: “In order to work…” gives a feeling of understanding towards the question posed.