In Xamarin Forms there is a serious need for a Rich Text Editor control that would allow you to do this such as highlight text, apply fonts, styles etc. I think a tool like this is in great demand among Xamarin developers. Currently there are some Open source controls that have implemented these features however they have not been maintained and cannot be relied on for enterprise solutions

A PDF Viewer component that you can put in your app will be a great addition to the suite. As a feature set it should at least support pinch and zoom.

Add controls to selecting dates/times that also support null or blank values.  Currently the DatePicker control that is provided as part of Xamarin Forms doesn't allow for a null or blank date.
Provide the ability to select date and time in single UI.

A GridView control will be a great addition to the suite. It should offer:
- Multiple columns
- Sorting
- Filtering
- Grouping
- Conditional Formatting
- User interactions

Available in the R3 2017 release. More information you can find here: http://docs.telerik.com/devtools/xamarin/controls/datagrid/getting-started/getting-started

the following exceptions occur when upgrading to Xamarin.Forms v 4.0:

System.NotSupportedException: Unable to activate instance of type Telerik.XamarinForms.DataControlsRenderer.Android.ListView.TemplateCellContainer

System.NullReferenceException: Object reference not set to an instance of an object
  at Telerik.XamarinForms.InputRenderer.iOS.SegmentedControlRenderer.OnElementDetached

The TabView control should support a swipe event to change the active item. Similar to the ListView with the IsItemSwipeEnabled-property.

Add a Map control to the product suite.

Add MVVM friendly commands for all list view interaction events: ItemTapped, ItemSwipeStarting, ItemSwiping, ItemSwipeCompleted, RefreshRequested

Add support for doughnut charts

Available in R3 2018 release. For more info on the donut series refer to: https://docs.telerik.com/devtools/xamarin/controls/chart/series/pie/donut-series

Already available for MultiDayView

TreeView control similar to the UI for WPF suite.

Available in R2 2018 release. More information can be found here: https://docs.telerik.com/devtools/xamarin/controls/treeview/treeview-overview

A great addition to the Calendar for Xamarin.Forms will be a Day View (Schedule View) where you can observe your appointments in a time-table.

There seems to be 2 issues with Telerik ui for xamarin and Xamarin.AndroidX.Core versions 1.3.2.2 and newer where A) Linker seems to be failing when set to "Sdk Assemblies Only" on Visual Studio 16.9.0.

The other issue is with Telerik RadListView and same  AndroidX.Core at runtime I am getting the following exception:

System.TypeLoadException: 'VTable setup of type Telerik.XamarinForms.DataControlsRenderer.Android.ListViewAccessibilityDelegateCompat failed'

Please advise

Customizable busy indicators that allow the end-user to understand that an operation is taking place at the moment will be a great addition to the suite.

More information on the BusyIndicator control you can find here: http://docs.telerik.com/devtools/xamarin/controls/busyindicator/busyindicator-overview

April 2020 Deadline

Apple will no longer accept applications published with anything less than Xamarin.Forms 4.5 after April 2020.

This is due to the UIWebView flag that is in Xamarin.Forms 4.4 and earlier

ITMS-90809: Deprecated API Usage- Apple will stop accepting submissions of apps that use UIWebView APIs starting from April 2020 . 

Solution

Please visit this documentation for full explanation. Just to share the highlights, Telerik UI for Xamarin will need to:

• Xamarin.Forms 4.5 or higher – Pre-release versions of Xamarin.Forms 4.5 can be used.
• Xamarin.iOS 13.10.0.17 or higher – Check your Xamarin.iOS version in Visual Studio. This version of Xamarin.iOS is included with Visual Studio for Mac 8.4.1 and Visual Studio 16.4.3.
• Remove references to UIWebView – Your code should not have any references to UIWebView or any classes that make use of UIWebView.

A good addition to the suite would be a textbox control that can be made read-only, while still offering text selection and the ability to copy text from it.