Well, currently Cubic Ninja and Zelda OoT are the ONLYPUBLIC entrypoints for a N3DS, and they will remain so until and unless someone/Gateway finds another exploit.
Although, the good news is one of the Karl3DS devs was able to install and use the MSET/DS profile exploit on a N3DS, which means there is a very big possibility that in the future you might need the Zelda OoT or Cubic Ninja JUST ONCE to hack into the N3DS and install the MSET exploit. Once done, you can boot into Karl3DS/Gateway using that MSET exploit without CN/OoT.
Also, and this is mostly conjecture, there was a miimaker exploit, which didn't require Zelda OoT or CN, but apparently it broke some of the functionality of the N3DS, so maybe if Gateway figures out how to make it work properly, then yeah maybe we won't need Zelta OoT/CN anymore.
Edit: So, while keeping in mind the above info, I would say maybe.
I hope fucking not. Let's be a realistic, Gateway has expand the scene on 3DS a lot, that's true, but latley, they do not look like the flashcard is in shape. I mean, I don't care if they need to find some big exploit, or some big entry point, or something. When you pay 60 bucks, or 80, or 90 because I see pages for 100 for a GW, you are not paying a mass-production flashcard which can be sol for less than 20, I am paying for support, I am paying for features and stability, and let me tell ya, this thing of Cubic Ninja, this is bullshit. Ninjhax is okay for homebrew launcher, thats the purpose, but when you need an external element to run something that buy, thats is bullshit. And thats what gateway do it right now. Release us bullshit. How would be if you buy a car, and to run that car you would need another car to make it on?
I hope Team Soon got back in the way the have too. I don't care if you need to do something complicated, you owe that to your clients as a brand.
seeing as karl3DS already ave their proof of concept downgrading MSET, i think its pretty obvious that at the very least gateway will do a similar setup......but that being said you will likely still need oot or cubic ninja to install the exploit.....so the answer is probably Yes & No....yeah you will probably need access to the game, but only the once to install the exploit then you can use the good ol' MSET exploit, and once its a one time install deal im sure the prices will drop as people can just install it and sell their copy so it wont be a hard game to get hold of