Right when the new Dex come out you can probably play with regular joe people with the old Dex just by saying "I havent had time to update to the new Dex do you mind playing against the old one?" and most people shouldnt have a problem. Now 2-4 months down the road dont try it. You should have the new Dex within 2 months minimum. It all really depends on where your gaming at, how strict are house rules, how legal conscious the gamers are, and just your local gaming community in general. If its friends it shouldnt matter... if its strangers or local tournaments I wouldnt even try it.