2) No. To explain:
I think he could have a reliable source, but they could mislead them with info so Nintendo doesn't track them down.
3) True, I didn't think of this. But again, another Nintendo fighter would be a weird and risky move. So I don't think they'd do it. However a Nintendo RPG is something I really want.
4) Pokebank has it to.
https://www.reddit.com/r/pokemon/comments/2mqkt3/with_pokebank_being_datamined_as_we_speak_there/
IT could still be linked to a possible 7th gen( If rainbow is real, maybe it's 7th gen, but I think that's to early)
I think it would probably be a 6th gen game though. I still think that the two games are gen 6 ones. If they wanted to make gen 7 on the 3ds, they could always patch pokebank to read it. That be pretty simple to do actually.
Hard to tell if this is the last smash bros from sakurai. He says this every game but loves the series. They tried making brawl without him, and when he found out, he asked to be put in charge of it again. He makes every game like it's the last because he doesn't know when they will make another or if they would. I think it's more him just letting the public relieve him after a game ends. He likes to take breaks and then work on other projects.
Even if one day he doesn't choose to make it, Nintendo would still probably find someone else to be in charge of it.
So Sakurai isn't needed with the game. I think GF have full control over what they do, but they like making pokemon because they got famous off it, and always have ideas for a next game.