I agree something should be changed about merchants that play caravan. Maybe give them a limit on how much money they can gamble with in a given amount of time. As it is now, you can simply buy the merchants entire stock of items and then take back all of your caps playing caravan.
Its easy to win loads at blackjack too, just save every couple of thousand and re-load if things go bad,
I think they should bring in poker in future dlc, imagine playing against bots/ghouls/mutants and being able to challenge winners/losers/cheater to duels like in red dead? Strip poker like dead rising 2 where you can win special equipment off of npc's?