I saw this post and at first I was enraged. I thought that this guy was stupid. I still do but it made me wonder the direction Ethiopia will go in moving forward. Islam looks as if it will stay stagnant proportionally but proselytisation into Protestantism is happening at a rapid rate. They tend to be more militant and so the future interaction between Muslims and Protestants will be interesting
Ethiopia will most likely break up, before becoming a shariah ruled country. Even with a clear muslim majority population; anyone with basic knowledge of that country knows deep down that it will never happen.
Realistically, if it happens, it's most likely be the regional states with a homogeneous muslim residents, i.e. Afar and Somali region, who will implement it.
Oromo are split religious wise, but they tend to be more open-minded, hence why some Oromo muslims even celebrate pagan Waaq religious traditions. The muslims and christians go well together and have been doing so for a long time. And they'll most likely keep it that way.
I don't think the Somali region would even implement it either. We've hitherto only had Addis-backed regional gov't/president, but even if an independent candidate democratically and with a public confidence gets power, the chance of it becoming a shariah region is slim. And will probably follow suit in the direction of other non-Shariah governed muslim countries like Egypt; full secular state but shariah laws with regards to certain aspects like marriage, divorce, inheritance and child custody etc. and other things they share with Christianity like on LGBT and abortion issues.