If WotC is going to leave Dual Lands in Extended, I wish they would reprint them at some point, because even the "newest" dual lands are about 6 years old. Since playing in sleeves was rare in the beginning, most dual lands have some degree of play wear.
You can find usable copies of duals at $10-12, but truly mint ones are generally higher.
I know WotC has said they won't reprint dual lands, but maybe they could put them out in some kind of "commemerative" or "collector's" set, or even create an exchange progam, so the number of duals doesn't increase, but the overall quality of the cards could be increased.
I'd also like to see this for the power 9.