Introducing a TabItem.IsTabVisible property would be useful. Currently, if you want to hide a tab, you need to remove it from the TabView.Items collection and cache it in a backing collection. Then, to re-show the tab, remove it from the cache and add it back to the TabItems (preferably at the same index if you've also cached it's position).
Add functionality to slide through the items like in a SlideView/Carousel.
Add support for tabs that cannot be selected
When you have declared a RadTabView with a single item and you try adding items at runtime - the new TabViewItems are added to the Items collection of the control but the UI is not updated.
Allow different width tab headers. For example, 200, 100, 100. Available in minor release 2018.2.727.250. It will also be available in the R3 2018 release.