You seem to have latched on to a few buzzwords and lost sight of reality, let me chip in my $0.02.
While I've not worked within the industry on UE4 personally (yet), I have spent a great deal of time working on UE3 and PhyreEngine titles, so let me make things a little clearer for you.

Each engine is designed with target platforms in mind, UE3 could target PC, 360, PS3, Wii (with some modification) and Mobiles, UE4 targets PC, PS4, Durango and Mobile, each have their respective engines and driver support within the engine, just because the engine can scale, doesn't mean it automatically scales to any platform you'd like without a lot of legwork, just because "it can scale all the way to mobile" doesn't instantly mean it can scale to wiiu, 3ds or vita, it scales to mobile because the legwork for that has been done, it scales to the other consoles for the same reasons, anyone approaching UE4 with mind to place it on a platform not included on it's target list is in for a great deal of work not only adapting the engine to support the hardware of the target console, but customizing the output of resources, managing the memory handling and of course writing their own API to handle graphics on the new platform, this has not been done for WiiU and UE4, and unless Nintendo themselves go to great lengths to port it then distribute their work to third parties (little tip, that wont ever happen), you're at best going to get one company that does it but wont share with others, because why would they share their work they paid their devs to create, so some other company can benefit for free?

And yet again, no company is going to spend the money porting UE4 to target WiiU when the changes needed to make the engine run result in a game that could just as easilly have been made on UE3 and perform just as well.

With the way third party sales are performing on the WiiU, third party devs are going to opt for the cheapest solution, which, unfortunately for you it seems, is to adapt whatever UE4 title they want to bring to WiiU to run on UE3, but yet again, i digress, You seem to not grasp that developers don't make games for the sake of the game or the gamer, they make it for money, and they're not going to pump hundreds of thousands, perhaps millions, into porting over a game that they know may not even break 200k in sales.

UE4 *COULD* be ported, but that's just the same for any engine, with enough sacrifices and comprimises, any engine could run on any modern platform, just because it *COULD* however, does not mean it *WILL* or that it's economically viable to do so.

UE3 is better suited to this generations hardware, PS3, 360 and yes, the WiiU, because it was build with the technologies these consoles uses in mind, as such it's the obvious choice for unreal engine powered games on PS3, 360 and, yup, you guessed it, WiiU.

But let me throw another spanner in your works - While unreal engine does indeed scale well, with automated processes for reducing poly count, texture resolution and so on, some areas it doesn't baby you through are shaders, and modern games use these extensively - so even if the ported version of a game were moved over, every single shader would need to be looked at, modified or removed to suit the different hardware, and without your chosen platform being one of the few UE4 is actually built to target, you would be doing this manually.

Thanks for the info but where does it say the engine will be UE3 if its scaled down?

THIS, anyone who says the ps4 will be scaled down has no clue what they are talking about.

Will it on par or upscaled then?