WhatsApp going the way of Friendster in messaging world?

Last week, Facebook announced the addition private messaging functionality for its Instagram app. A direct shot at Snapchat after the company rejected Facebook's reported US$3 billion dollar offer a few weeks ago. The first thought that popped into my head upon hearing the news was...why is WhatsApp still around? 

WhatsApp was one of the first messaging apps for the iPhone. The company has built up a large amount of users, but feature-wise it has been overshadowed by numerous other apps including LINE, Facebook Messenger, and Skype.

Over time WhatsApp was released on all the smartphone platforms, but there were limitations--the app only runs on one device and it doesn't run on iPads, tablets, or desktops. It's essentially an SMS/MMS replacement for your phone. Use two phones? You can only run WhatsApp on one of them and launching it on the other causes a re-verification process to happen, de-coupling it from the previous phone.

These days, people move between devices and computers repeatedly. For me, regardless of device I'm on (laptop, desktop, tablet, or phone), it's great to have access to all my messages and the ability to use a full-sized keyboard if I'm on the appropriate device. With WhatsApp, if I'm in front of the computer I still need to pick up my phone to correspond with people messaging me.

Why are people still using it? Is it a case of, "My colleagues and friends are all on it so it's too much effort to switch?" With the hundreds of messages one gets in a day, think of the time saved by having messages route to the device you're using. This seems like a feature worth switching for.

What do you think? Will WhatsApp become the Friendster of the instant communication world or will they manage to retain the loyalty of their millions of users?