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?
It's difficult to say at this point what will be the effect of crypto on local economies but yes currencies will obviously not survive if crypto becomes mainstream. Think of it yourself why would anyone want an additional currency when there is a big currency which everyone is using, moreover it's just a myth these days that everyone can't do online transaction, I have even seen street vendors in my city accepting Payments digitally. In India especially UPI has brought a revolution and this can also help people in adoption of Cryptocurrencies.