I guess everybody who wants to get a game ready for the 2017 NX launch.
So, basically the companies that produce AAA Games that need 2 years.
Indies will get Dev Kits in Late 2016. Should be enough time for them to get Games ready for the 2017 Launch.
If the dev kits are public knowledge now, that implies 2016 launch. Did anyone publicly have PS4 dev kits in 2011?