The World Tree will undoubtedly become a staple card in 5-color decks in commander format. It may also find its place in standard, or even modern and pioneer alongside Niv-Mizzet.
But it's the commander format that will drive the price of this land card. The current market value is still a tad too high, and it should see a slight downgrade to about $9-10 a piece, when things settle down.
It's also interesting to note that The World Tree started at around $30 per card, then dropped off to $7-8 and then corrected to the current $14-15 price tag. This just shows how unsure marketeers are on this one.