There is amazing new browser for Pharo, Calypso, which has remote browsing capabilities (but probably different remoting/proxy layer than gt tools) - is possible to utilize this project for remote Gemstone browsing in future?
Calypso itself is independent from remote communication library. So it should be possible to implement it with Gemstone API.
Then model part of Calypso should be loaded into Gemstone image. Here many compatibility methods will be required to support model in Gemstone because it is about reflection and Gemstone has many differences. Imaging how #senders is implemented.
Next part is how Calypso react on system changes. It uses SystemAnnouncer events to notify views. And I have no idea how it works in Gemstone. Maybe Calypso can not be "active" there and manual #update commands will be needed. (Imaging two browsers are opened on same class/method and one browser add/edit method. Another browser should be updated)
Another difficulty is refactorings and doIts.
So nothing is impossible but it is completely not out of the box. And it looks like real project to support Gemstone.