I agree that WDTV or WDTV Live is no longer a viable for the popular streaming services, but it is the only viable option I have found to support streaming my personal collection of over 10K media files of which 85% are in the .avi format. Roku does not support the .avi format. As a result I have a Roku box for external streaming and I use the WDLive or WDTV box for my internal files. I have had no problems with mkv files on my current WDTV players which are 3 years old. I like the easy to use menu system on the WDTV to access my NAS files that I get to use the Network Shares option on the WDTV streaming box.
I recently purchased a certified refurbished WDTV box on Amazon. Even though they indicated it was out of stock, I placed an order and got one with 1 week.
Amazon: Western Digital WDBYMN0000NBK WD TV Media Player, with Wi-Fi and Ethernet connectivity (Certified Refurbished)