While I strongly support any business model that tries to escape from the typical ads monetisation strategy, we can see (two years after this post was published) that not relying on ads has not been the best long-term strategy for WhatsApp for two reasons:
1. They didn't manage to stay independent and had to sell to Facebook. I always thought that they had a very good chance to expand their product and built a platform that could truly challenge Facebook, Twitter, etc.
2. Now that they have been acquired by Facebook, we know that it is only a matter of time before an ad product is introduced into the service.
They didn't have to sell to FB they chose to. They had a history of flipping to paid versions of the app to cover costs and reduce growth. Their actual competitors were carriers who charge exorbitant SMS fees internationally. At ~500M users their plan to simply charge $1/yr would have covered their costs.
This is something that never really sat right with me. How were they going to extract the $1 from every user? Most of their users do not have, and may never have, a credit card and signing up with every cellphone carrier to get your yearly $1 would have been a nightmare. I am not sure they would have gotten $1 out of even every 10 users.
I don't see it that way. After selling to FB it became clear that hey intended to launch VoIP. If they actually wanted to launch a high-quality product, better voice service than the one offered by carriers (and therefore much better than what Viber has to offer), they would probably have struggled to do it without the help of FB. Every carrier on earth would be against them.
A carrier would give a lot more thought to disrupting a competitive voice service provided by FB (who already have many agreements with carriers worldwide regarding data usage) than an independent and not particularly well funded (by carrier standards) company like WhatsApp.
