It is with a bit of sorrow that I write this post. After seeing this article in the London Free Press, I was able to confirm that several of the carvings have been designated for removal, as they have been deemed unsafe. The following carvings are either already gone, or will be removed soon, according to Tourism London.
On the subject of the expected life of a carving, Dave Broostad of Hamroad.com, who have commissioned new trees, had his opinion printed in the paper.
Convergence @ 23 Peter St.
Woodfield 1840-2007 (already removed)
Come Together and Grow
There are no plans to re-install these carvings, in contradiction to the LFP article linked above.