Except for phones deemed "Not available", the only phones still "Under testing" are Verizon's. Every other carrier has the update available. The Lumia 521 from Metro PCS doesn't count (IMHO) because they are owned by T-Mobile, and the 521 for T-Mobile has the update available, so it will probably be available on Metro PCS any day now.
Either Verizon seriously dropped the ball on this one, i.e. they tried to get the update out but failed miserably, or they didn't even bother to put any real effort into getting the update out. Either way, I'm certain that Windows Phone customers are going to be putting a lot of serious consideration into whether or not they should stick with Verizon. ATT seems to be a much better bet. WP usage is still very small, but it's growing every day and the hardware and software get great reviews just about anywhere you look. Add to that the recent announcement that WP 10 is coming out and WP8 devices will be able to update to it. If Verizon screws up that update as bad as they've handled the 8.1 rollout then they will look like an absolute joke. The "most reliable network" won't mean a thing if they refuse to push out available updates. Well, for Windows Phone customers anyway.
At any rate, it's painfully obvious that something very fishy is going on at Verizon with regard to Windows Phone. And I think it's more than mere incompetence.
Look it's been well known if you're looking for fast OS updates then you need to go elsewhere because Verizon will most certainly be last or next to last behind Sprint. Until Verizon phones stop coming with CDMA radios in them that will be the case.