Okay, this is either misinformation, or maybe Arcee is just one of the bikes, not the combined form. Maybe Fox rides Chromia. Or maybe Bay has some even more ridiculous idea in mind, I wouldn't be surprised.
I really don't care if Arcee dies or not, as long as it isn't pointless. We need PLOT in this movie, Mr Bay, not irrelevant narrative strung between massive explosions. I'm all for explosions and giant f*cking robots doing battle in the streets, but I'm also all for substance.
For the people mentioning the TF1 Jazz death: Jazz wasn't "black." He was voiced by a black actor. Cybertronians do not have ethnicities of white/black/red/yellow/green. If anything, Jazz's race is Autobot. Or Cybertronian, if one considers that not all TFs are Cybertronians (Junkions, Paratronians). So, by that token, it is impossible for Bay to have killed off the "black" bot, literally (and literarily) speaking.
One could transfer this same principle to Cybertronian gender, and consider that there really is no such thing as male or female Cybertronians. Maybe their physical resemblance to human genders is purely coincidental.