There's a bit more to it then that, (The last line is roughly "The little lady screams...and
roars") but keep in mind Hata drew it way back when Golden Week had
just ended. We didn't know who Luca was, what building Nagi was running up, or anything about her moving into a new mansion or trying to become a doujinshi artist, ect ect...It was a lot more interesting a year and a half ago then it is now, though we still don't know what exactly gets Nagi so upset/determined.
As for the actual chapter...
I really doubt Luca is going to actually die, but I could see her suddenly falling into poor health at a bad time. She's been pushing herself through injuries, poor nutrition, overwork, stress and who knows what else for a long time now.
Honestly I kind of suspect this is a prelude of Luca being forced to move in with Nagi "for her own good" more then anything else.