Originally Posted by Wolverine
Speculation runs both ways, my friend. If I don't have the reason to believe that Minato could summon himself, then you have no reason to doubt Obito's strength either since you didn't know the complete list of his abilities. How he acquired them or whether it even made sense for him to have those abilities is definitely questionable and you're right on that stance.
Minato's jutsu is a summoning. Which means that he travels across dimensions to move from Point A to Point B. Irrespective of where he is, he should be able to move back to the real dimension from Kamui's alternative dimension since he has the summoning kunai that acts as a beacon here, and he already can summon himself at will.
Again, I don't go by absolute proof here, just my application of logic with regards to the applicability of the jutsu. Nothing more.
Actually, Kakashi pointed out the possibility that Space/Time jutsus use dimensions independent of each other
. Which was to explain how he was able to attack Obito in the Kamui dimension. Minato's FTG jutsu is a Space/Time jutsu. If they run through independent dimensions, he would've been stuck in the Kamui dimension until/unless Obito released him.