You truly think Nintendo would be well-advised giving NX kits to Rockstar? Why would Rockstar care at this point about the NX? When was the last time Nintendo did anything for Nintendo machines? Yes, they could port GTAV and yes, that would be a good thing, but it's an old game by now that's already on every other system, so it probably wouldn't have that big of an impact. Nobody was excited about playing an old version of Batman on the WiiU, I doubt a GTAV port for NX would kick up much fuss.
Nintendo shouldn't just support the big studios that MOST LIKELY aren't going to be too hot on putting a lot of development resources into an unproven system with an installed base of 0. They should have a few people who're spotting out smaller studios that could theoretically have shipped something on NX at or near launch - And they shouldn't be as crazy secretive about it as they are. Yes, Nintendo is constantly and always being copied - for god reasons. But we live in a time where what really matters is good software, not another hardware gimmick.
Nintendo should be out there, trying to get at the very least timed-exclusives for their hardware and work hand-in-hand with developers of whatever size. We like a secret as much as the next guy, but if your entire studio is dependent on software and you're not getting the software if you keep everything close to your chest, then maybe, just maybe, running with the same old strategy that worked 15 years ago isn't the right strategy anymore?
To be really honest, I think a GTAV port with some additions (and well done overall) wouldn't be as bad as some late/very late ports Wii U got at launch. The reason? GTAV is still selling amazing despite being more than 2 years old, thanks also to ports on other platforms.
About all your posts: I simply hope that dev kits general distribution starts soon enough so indies developers of all kinds can be able to bring their games on the platform without problems. Combining some of the stuff from WSJ, Trevelyan's third party dev and the recent Tamaki's rumour + John Harker's posts, I'd go with the following schedule
Before E3: Some developers start talking with 3rd parties about NX (John Harker knew about this, so I suppose Ubisoft was involded since then)
At E3: More widespread discussions with different parties about NX (Fortune article, then confirmed by John Harker)
July 2015: DQX and XI get "leaked" for NX directly by DQ producers themselves at the conference where they announced DQXI
October 2015: WSJ shares the news that SDK distribution has started, alongside other tidbits (two "powerful" devices, "industry-leading chips"). Around this period, there's also John Harker saying that Nintendo is throwing NDAs here and there, a huge amount of them, which makes me think this is when Ubisoft received dev kits as well. Recent Tamaki's rumour makes me assume this is when EA received dev kits too.
February 2015: We've started hearing more from Western developers, through both Trev and Tamaki + random tidbits here and there.
What I can gather is that the key partners are publishers or developers with a relevant and ongoing relationship with Nintendo / major publisher that Nintendo feels the need to get on their platforms again (EA). I wouldn't say it's impossible that some indie developers who are nearer to Nintendo are among key partners. They got access to dev kits before anyone else. There's a date for distribution of public dev kits, but it can't be shared right now due to NDAs. Also, there's a possibility of Early Access before that date, but there's a lot of bureaucracy involved.
I don't know when you asked about a dev kit to them, but I hope you can try again and that you get a better answer this time.
Also, now that I think about it: that rumour from Trevelyan listed this too
The Developer’s Nintendo Account Manager stated that Unity and Unreal Engine 4 will both be ready in time for when developers outside of key partners are able to purchase dev-kits of their own.
And now we have M3d1on saying something similar right in this thread (validation pending on the veridicity of what he said, though)