Oftentimes, yes.
If regularly root-pruned, a bonsai specimen will be incredibly vital....
Once placed in the ground, the tree would take off like a very well-rooted cutting.
In-ground (or yard bonsai) is called "niwaki," I believe, and there are numerous
techniques to maintain these larger specimen.

Josh

Yes, those pics I posted a while back of the ficus and shimpaku in the ground in Da Lat were 'Niwaki'. Those are being kept in the smaller size though, any of them could have been jerked out of the ground and potted up. Biggest was about a meter tall.

Bob

Hi,

Yup, the'll grow back to a full / normal size if put in the ground and left unpruned.

If you are intending to have a large sculpted tree, then yes, Niwaki is a term used for garden trees in Japan (noun). The verb / expression for this craft is called 'Ueki no Te Ire' which basically refers to the art or practics of sculpting trees (topiary).

Check out this link / about 70% way down the page:
http://ferncreekdesign.org/japanesegarden.html

HTH,
Cam.