Scaling up would be hard. I think the E2 is a 4 seat across aircraft. It's maximum capacity configuration is already quite long (42m) with ~120-150 seats. A320 is like 38m long with ~200 seats (6 seat across).
Scaling into the A320/737 range would need a brand new design with wider fuselage probably. I'm not saying that Embraer could not do that, but sticking with the E2/A220 size range seems to be a winning combo - until recently (A220), they had no real competition from the big two. Maybe with the more recent weakness from Boeing, Embraer might want to consider a 737/A320 class design, but these things take time.
Also, as much as BRICs is a thing, I don't think Brazil would be too fond of selling Embraer to China.