I hope (and feel) like the ruse will not work.
WhatsApp and Instagram are much stronger brands, and are not already branded "Facebook WhatsApp" or "WhatsApp by Facebook".
That's not going to change.
Well, the splash screen says "Whatsapp from Facebook", and the description on the Google Play store starts with "WhatsApp from Facebook is a FREE messaging and video calling app."
So, it's out there, even if people haven't changed the way they think.
Disclosure: I worked for WhatsApp until 2019
Google is responsible for alphabets web services. Check out Wikipedia for actual examples like waymo (https://en.m.wikipedia.org/wiki/Alphabet_Inc.)
We still think of Alphabet as Google. So while Facebook may effectively become Meta, people will still say "Facebook does X" when they should technically mean "Meta does X".