So, it's been established that you're not going to get what you paid for that lens. After all, when you buy any lens new it's not easy to get what you paid for it within a few years. And a lens that Canon is kicking the legs out from under? Forget about it.
Selling it now won't get you the price you want, but at least you'd get some use out of the money already spent. And that's a win. Spend the $600 or $650 you get for it and buy a used lens that will appreciate in value in the next few years or use that same $600 to buy and sell several lenses in the next few years. I've had some real nice glass go through my kit over the years and I've essentially paid nothing for them. In fact if I had to sell everything now...completely cash out, I'd get my initial investment back and then some.
Sell that 24-105, take the loss, and buy something used that you can have fun with.
Think about what you'll gain, and not about that temporary loss.