Perhaps what we need to do is actually truly start treating ideas like property if people want to pretend that they are property.
When you copyright something, you need to put a dollar figure on the total value of that idea. You can say the idea is worth $1. You can say the idea is worth $1,000,000,000,000. It's completely up to the owner to determine how much the idea is worth. If you then want to sue someone who "pirates" your idea, the damages are based on the stated value of the idea divided by the number of copies of that idea that have been created. So in the case of a game, if the developer claims that the game as a whole is worth $10,000,000, and has sold 100,000 copies, then the value of a pirated copy is worth $100. Figure treble damages, plus court and attorney fees and that is the most they can sue for. No more of this $150,000 per work garbage, so that copying a mix CD for your friend is no longer worth millions of dollars.
Now we get to the fun part. Property is taxed. Every year, a copyright holder needs to pay for the tax on their ideas. If 2% works for real property, then it certainly works for intellectual property as well. Every year a copyright holder needs to pay 2% of their stated value for the idea as a tax. Claim the idea is worth nothing and you pay nothing. Claim it's worth billions and over time you'll pay billions. Stop paying the tax and the idea now falls into the public domain, because clearly the owner decided it wasn't worth paying upkeep on, and the idea must be worth nothing.
Voila! Copyright can last forever if someone believes their idea is valuable enough to continue paying for it. If the intellectual property owner doesn't want to keep paying tax, it's entirely their choice.