I don't know, nothing lasts forever, and one might 'die' at the hand of the other. It could easily happen through acquisition as he says.

What if the merge? _shudder_

Well... Facebook is worth ~$15bn and Google is worth ~$740bn. I'm sure Google could scrounge up 2% of it's overall worth to buy-out Facebook... but then, Google already know everything about you, so for them, Facebooks data is worthless.

Your Alphabet/Google market cap is about right, but Facebook's is 442.50B as of today.