I think the only correct pledge that might change Nintendo behavior would be to pledge against buying Nintendo 1st party software. I myself wouldn't be willing to do that, since they still make some of the best couch multiplayer games that my whole family can enjoy together (like Nintendo Land and Super Mario 3D World).
Buying 3rd party software on Nintendo system is pointless. So those people that enjoy Nintendo games, know they just need to have the Wii U as a secondary console, enjoy gaming most of the year on that other primary gaming system and then dust off the Wii U whenever some really stellar Wii U only game becomes available.
There is no way that I would choose buying an Online Centric multi-plat game on Nintendo console over even the PS-Vita, let alone the X360/PS3/XBO or PS4. The blame for this is entirely on Nintendo. This is Nintendo problem to address, not the gamers or the developers problem.
There is also very little chance I will buy any multi-plat game on Nintendo console over the PS4 version. The reason for this is the PS4 is just really fast as an OS and also once the game is launched it will look/play better. Also, my online friends can get me on Party Chat even as we play different games. Prior to the PS4, the X360 was the best system to play multi-plat games on.