You're essentially describing hawala.
The difference is that in the remittance destination country, the roughh equivalent of a "hawalder" can work independently and doesn't need to have any trust relationship with the hawalder receiving funds on the other end.
Where is the incentive to add the extra layer of using Bitcoins at both ends though?
Lower fees for one.
You can only compete with WU and hawala if you can offer the same ease of access - a dealer in virtually every neighbourhood.
I'm wondering how long it will take current hawalders to figure out they can use bitcoin to do deals on their own. Bitcoins don't yet have much value for the recipient of a remittance transfer but in bulk they do have value to an enterprising hawalder, such as being useful to pay for purchases made abroad or to sell to a local investor perhaps.
a stand-alone money transmission service isn't going to be profitable in many regions.
That's the difference between Bitcoin and a Western Union. A WU agent location needs lots of volume to pay for the overhead. An individual who provides a method to cash out your bitcoins can be profitable on every trade. It doesn't need to be a full time operation or need to start out as a part time gig even. There no doubt are individuals with a little extra time and money that will do this exchange "as a favor" to be able to earn the 5% or 10% that doing so will bring. And then word gets out and in the following month there are two recipients who need this favor. And then it is four, then eight, and pretty soon this individual now has this sideline business doing cash-out service.
Also, then consider how basic business sense starts to take over. If I am offering a Bitcoin cash-out service to you, and you turn around and use that cash to pay for your mobile phone refill, then why don't I just start selling to yo mobile phone refills for bitcoins, and earn the profit from that sale as well?