If FFG has demonstrated anything at this point, it is that there is no parity in their lineup.
Good point, it's not like they have to release imperial cap ships. They clearly don't mind that the Imp's have a 2-1 advantage in large ships, so they may not mind that the Reb's have a 2-0 advantage in Huge ships.
But even if they do release some Imp cap ships, it's much more likely they'll release something on par with the CR-90 then anything else... That of course assumes that the CR-90 sells well enough for them to even consider an Imperial version. If the CR-90 doesn't sell well, then it's unlikely we'll see anymore ships of that size.