As much as I want Retro to do a new Star Fox or Metroid game in the vein of Prime, I want to see it do an original IP where it has full freedom to do whatever it wants. Those folks deserve that opportunity.

I think this is on the money. A lot of articles presuppose that these hirings are for one giant project. I think Retro is picking up bodies to tackle several projects at once.

Donkey Kong 3D + Star Fox U

Well, I don't know a lot about game design, but isn't it a bit strange to hire new artists at this (presumable) late stage in development? I would think stuff such as character/environment art would be created at the beginning of a new project.

Perhaps they really are working on more than 1 project? 'Cos they wrapped up development on DK Country Returns WELL over 2 years ago (the work they did on MK7 can't have taken up much time/effort), so whatever game they're working on ought to be quite far into development by now, ready for release somewhere in Q3/4 this year (the latter being imo entirely).

Besides, some of the new staff they hired are apparently on contract, meaning they're not permanent staff, but specifically hired for a project, after which they're presumably let go. Hiring characters artists and the likes in such a way would hint to a new project in its initial stages, I would think. Then again, I could be dead wrong. But the idea of 2 Retro titles in development is definitely exciting. Metroid Prime 4 + a new IP/revisiting an old, dormant one from Nintendo? Yes please. We'll see, I guess. Nintendo's SO good at keeping secrets. >_<

yes it is very likely that the new people are for a new project other than the one they started after DKCR

I think there's a possibility that they're making a game

Lol, actually there was a rumor some time ago saying that Retro was working on an engine for the Wii U, apparently they show it to Epic and they were impressed. So they may be working on other things than games. 

I said there's a possibility ._.

I'm really excited to see what they are working on. Retro has so much talent already and this just adds another later of quality.

They better show something at E3. Something that is even bigger than the Monolithsoft game from ND.

I hope that Retro's game will surprise me and I would not question the thought of them making two titles at the moment.