I can only see good things coming from this.
Servers: who said they kept all of them in different countries? The problem will be, from my perspective, downloading new content from now on.
Performance? Get some RAM and a SSD. I doubt UE4 will make this any(much) better, since text, UI elements and windows mini-freezing and sometimes lag.(Full-screen versus windowed)
EU and NA merging ... playing on 110 ping is something. No European would play on 250 ping.
Uniting players is a great thing. Finally, the maps won't just be full of nothing and one AFK rando. But, as a Jinsoyun players, I've yet to meet more than 1 angry Arena player(but we have lots of bots in exchange!). Time to see some players!