Used games are not a problem.

I think the reason that people are so willing to shell out $60 for a game, is because they know they can sell it on later to get some money back. If they couldn't do this, I doubt people would buy as many games at full price. While yes, publishers are losing some revenue from people not buying games new, they are gaining revenue from people buying games new, knowing they can get some of the money back later. It balances out in the end.

Used games are also a great way for kids, who don't have enough money to spend $60 on a game, to get into gaming. And when they grow up, they will spend $60 on a game, so in that sense, it can be very beneficial for the industry. If new people didn't start gaming, the industry would gradually die out. I used to buy a tonne of used games, and if I couldn't get games for that sort of price, I wouldn't have gotten into games on anywhere near the scale I have, and I wouldn't be buying games for full price now.