[FungalRaincloud]

It's plausible that they could just compromise the security, intentionally, without telling anyone (and without anyone being able to easily tell).

I think what's more likely, at least in the case of WhatsApp, is that they would just not make an announcement when they remove E2E encryption entirely. The security community would certainly complain, and long-term, the traffic they are currently getting from parties of any interest would move somewhere else. But in the short term, it would compromise the security of a substantial number of their target users. It's plausible that, without a public announcement, many 'nefarious' users would continue to use it for a few months.

[rocqua]

I'm more worried about a trigger-able mode of whatsapp that silently disables E2E encryption on a specific phone. The only way to figure this out is to catch the app in the act.

It seems possible that WhatsApp could be persuaded by the government to implement such technology.

[FungalRaincloud]

Something that does concern me about WhatsApp is that backups of messages (by default, it seems, put on Google Drive on Android) are not encrypted. I'm not really sure why. There's not a compelling reason that I can think of.

[rapsey]

Or already has and is under a gag order.