I'd like to bring up my recent theory about Naruto and the FTG technique as I gave it a little more thought and reformed it a little.
Now let's take a look at Minato's FTG and Madara's unnamed tech. Okay, Minato's tech is a space-time jutsu and he needs special seal tags to use it. Madara's unnamed jutsu is also space-time but he is able to transport himself where he wants to. He has also said himself it is within his power to locate Taka on their way to Konoha and appear in front of them to stop them. He also located Naruto and a little later Danzo as easy as if he could just sense their chakras and then appear near them. And how does Minato use the seals on those special kunai? Yes, that's right, he senses where they are which enables him to use the FTG in the first place. I am not saying Madara is a sensor, but maybe he just has a way to locate a certain individual's chakra.
Hmm right Naruto's Sage Mode will enable him to use FTG in a more advanced way than his father and then he can match Madara's space time tech
Now to turn our attention to Naruto. His sage mode grants him sensory abilities. So if he learns the FTG maybe when he is in sage mode he won't need the seals as he'll be able to locate people's chakra from a relatively long distance (as we saw when he chased after Sakura when she went to track down Sasuke) and appear near them. This is all there is to my theory meaning sage mode is highly unlikely to enhance FTG further than that. After all, what more does Naruto need?
I'd be thankful to hear your opinions especially any constructive criticism