↑As you mentioned, currently there are three features in the map, which are Destructible Rocks, Grass and Xel'Naga Watch Tower. And as you can see the answer to the same question in Q&A Batch 47, our development team will be pleased to add more if we can design other features which will make the game more exciting and balanced as well.
However, in my opinion, it seriously affects gameplay itself and the balance as well, so that it needs to be very careful to find and add more features, for keeping gameplay still exciting and balaced.
Right now, there is no other addition to the map, other than those three features. Cydra. 2008-01-08. Any word on other. Battle.net StarCraft II General Discussion Forum. Accessed 2009-02-10.