We already port back with all of our items in our backpack pouches, adding the option to port you cart back too is going to kill this game imo.
There needs to be some risk involved for being able to transport such a large amount of goods.
I could easily go naked with an alt and never risk anything at all, if you kill me I'll just, "thanks for the free teleport back to my city!"
With zombies coming based on the way they have been described to be able to loot players/bins and use our gear against us and roam into our cities - and then you throw in carts that don't port back with you we will see lot's of players returning to play this game imo. (also will create more interest from those that are considering purchasing the game)
People need a reason to play and this game could get really good really fast with what I mentioned above.
Please, I'm begging for no cart-porting!