No, that would make growing new cities impossible. Right now when you build a city the first thing you wanna do is get a trade route. I think it was +3 production, +3 food. I guess losing 1 of each isnt that bad, but still thats the whole point of intranational trade. In fact I wish that they would increase it with a policy. Have a policy where cities founded on other continents get double yield from intra trade routes. Coloniliaztion has always been way UP in civ compared to the real world.