[unhammer]

I disagree. Most of my contact list doesn't use TextSecure/Signal; when I want to send someone a message I don't want to have remember if they use textsecure in order to open the optimal app for messaging them with. Maybe I'd even first open textsecure, then be disappointed that they're not in there and have to open the plain sms app. How annoying that would be.

Nobody needs SMS if everyone could just use the same app. But my brother uses a dumbphone and my mother uses an iPhone with nothing but iMessage and I use an Android and don't really feel like installing whatsapp or whatever the latest fad is just because one or two of my friends has it. Over SMS I can communicate with them all, and if any of them ever install textsecure I get encryption as a bonus.

[nzp]

They're planning to drop support for encrypted SMS fallback (a decision I have mixed feelings about), but plain SMS functionality will remain in the Android client for the forseeable future.