It is really a bless for poor countries. But some third world countries do not accept BTC yet. But why are they doing it? They can easily be benefited through bitcoin. So, they should accept it quickly.
How could you say poor countries can benefited by Bitcoins?
Let us assume tier 3 countries make Bitcoin as legal mode of payment. But still people will prefer payments in fiat currency as there is no charge for it. Also poor countries are mostly technology backward. When the majority of the public living on $1/day, how could you expect them using Mobiles for payments.
Also if we say Bitcoins provide source of income to people then this concept is also limited to certain class of society. Not everyone can make their livings with Bitcoins. You can't teach people how to earn via Bitcoins, people can make their living out of Bitcoins only on their personal experience and skills.