No such thing as Islamic clothing. Islam is a set of guidelines given by Allah (swt). Afterwhich it functions as a cultural filter. What is halal in the culture is good, and what is bad is haram. Power to it if an Arab garment ,khamiis, passes through said filter. However, as Islam is a religion for all people and not all cultures wear that particular type of clothing, this does not constitute it Islamic apparel.I'll address your points one by one:
●More people are wearing Arab clothes
I assume you mean the hijab and Qamiis. Both are which are Islamic clothings that have been worn in our culture since we embraced Islam roughly centuries ago.
●People are starting to not speak Somali at all and instead speak Arabic
That's just simply not true. Somalis overwhelming speak Somali and the minority of the ones in the West who don't speak Somali well, speak English not Arabic.
The vibe I get is you saw maybe an isolated instance and projected that to be the norm.