I don't exactly know ... 

Considering that they would have to adapt some of the code to make it run on the WII U I would imagine it been the opposite since the cost of a dev kit is relatively trivial compared to the man hours poured in to do the software engineering ...

It's most likely the LICENSING FEES to allow for a bigger download size that's the expensive part and the reason why Microsoft or Sony do this is to maintain the amount data usage happening on their online system. When you have millions of users downloading a game from either Xbox live or PSN a GB can make all the difference in saving millions of dollars ... 

Maybe Nintendo offered a lower fee for a bigger download size and they concluded that switching to the WII U may have been the better idea ...

From a failed handheld to a failed console :P

Do note that this cost only applies to the PS4 so the cost of a vita dev kit is most likely cheaper when you factor in the less costly hardware and possibly less frequent software support as time went on ...

Maybe its because of potential user base? Its been shown that Wii U indie games do get support vs the twins.

I hated the guy who tried to chansaw off your private parts

It looks really good. I wonder why Nintendo doesn't make a deal with some indies and funds a limited retail release of some of the bigger indie games. It could help during the droughts in the eyes of the public that doesn't really use the eShop.

Will this be eshop exclusive or also retail?

I'll take it.
Reminds me of 'Sadness' for some reason ... Still want that game ...

This wont come to wii u. If it ever sees the light of day it will go over to ps4 and x1.

eShop exclusive, most likely. They might be able to pitch this to some publisher, who'd have the power to make this anything other than a digital-only release. That said, unless it's Nintendo itself, it's really unlikely.