i think he would of escape ,minato had all the tools , fgt & his mark kunais he could of easily transport back to the real world
I doubt he would have escaped.
Minato knew that if he got touched he would have lost and been sucked in, if he could escape why would he be worried about this?
Obito, who has full knowledge on his abilities was 100% sure about his victory if he sucked Minato in.
As I explained in my post, Minato doesn't know where he was being sent to, so he could've just been playing it safe. Obito doesn't know the exact physical mechanics of Hiraishin well enough to be able to correctly determine whether Minato could escape boxworld or not.
I mean, for pete's sake, Obito thought chains would be a good method to restrain Minato! I don't think we can really take his judgement into account on this.
There's no concrete evidence either way.
And does Obito know the exact physical mechanics of Minato's jutsu to the point that he could accurately determine whether Minato could escape his dimension or not? I think not.
I mean, he thought chains were a good weapon against Minato, for Christ sake's!
to my knowledge no one with a summoning contract has been warped by Obito. Who knows?
All that is needed to know about his jutsu, is that he can warp from Kunai to Kunai, Obito knows this so he should be able to deduce whether he can escape his dimension by warping to a Kunai in the real world.
Obito also thought that a chain was a good choice of weapon against possibly the greatest combat ninja of all time.
I'm gonna have to go with "Obito's judgement is a bit suspect" on this one.
You just have to put yourself in Minato's shoes and the answer is obvious.
How the hell could anyone know where would that technique (Kamui) teleport you to? How could anyone know that it sends you into a relatively "safe" place? How the hell could anyone know whether it would send you into some hellish place filled with lava/acid/whatever that would kill you as soon as you arrived?
That's the danger of T/S Ninjutsu.
Minato had no way to know any of this about the technique.
So of course he had to make sure not to get teleported no matter what.