We plan to release all our product for nopCommerce 2.6 by Friday July 6th.
As to removing our plugins for the themes, we do not intend to do that as our plugins afford a more configurable functionality as they are at the moment and moreover we intend to add more powerful features to them in the future. The Ajax Cart for example supports adding products with attributes via a mini product details fly out view, something which is not in nopCommerce 2.6. As to out immediate plans for the cart we intend to add a much more detailed pop up dialog to the cart, showing what product was added to it, and allowing the user to navigate to various pages and take various actions. Regarding the Instant Search, we intend to add a Categories dropdown like:http://www.imdb.com/
Please note that our themes have a setting to enable\disable every plugin in them. So should you wish to use the default nopCommerce functionality you will be able to do that.
I hope this is useful!