According to Economic Confidential blog " IMF says, Crypto Assets May Displace Local Currencies in Developing Countries". Source: Economic Confidential, Facebook page..
Bitcoin is taking over the internet for online transaction, therefore, most of the local currencies in the developing Nations are affected.. because developing Nations are not inclined in the e-currency transaction while the new generation youths use the e-currency for transactions. That making the local currency weak.
Can Bitcoin really weaken the Local Currencies in the Developing Nations?
I think it can weaken US Dollar and it is already doing it as number of transaction to buy good and services by using crypto is increasing worldwide but not local currencies. In fact in third world countries there is huge trend in youth and IT Professionals to invest/trade in crypto currencies to generate income as well as through mining, airdrops and bounties and local economy takes benefit of it.