As usual Minato is underrated, but what some people forget is that actually Minato has better speed feats than Naruto, and he has that with far less screentime. Minato has never been hit by someone unless he wanted, not even by Tobi or Raikage or even others in battle so far we know, when both Tobi and Raikage managed to push back Naruto in multiple occasions. Minato owned Tobi in less than 2minutes. Naruto can't even hit Tobi without Kakashis help and they were four(Naruto, Kakashi, Gai and Bee). It's why i believe that eventhough Naruto closed the gap in speed, Minato still has much more experience in it, and FTG is an instant teleportation technique, what many people forget, so no matter how fast Naruto is, he can't be faster than Minato.
How can he touch Minato if he can't even touch Tobi? Sure Minato doesn't have Kamui that makes him difficult to touch like Tobi, but how does Tobi actually manage to know where Naruto could hit him? How does he manage to know when to teleport parts of his bodies to dodge? He knows it because he has time to see it and use his kamui in the exact same time to dodge and counter-attack. Replace Tobi with Minato and instead of using Kamui, Minato can simply use FTG to dodge, or even take this opportunity to counter attack like he did against Raikage for example. Minato was able to crush Tobi with a perfect timing created in less than one minute when he even had no idea about his opponent, not even knowing how his jutsu works. It's where Minato is greater than Naruto, it's where it would be dangerous for Naruto if he wants to battle him in a battle of speed, especially when you know that close combat is dangerous for Naruto as well. If he gets marked for example, the fight will be almost over, since Minato could appear next to him everytime he wants and finish him instantly.
If Naruto uses TBB, Minato can redirect it to him, so he will only kill himself. If he wants to speedblitz Minato, like i've said, he risk to get marked by him and if he manages to do so, he is done for. So only chance is to use KM clones as feints and use this opportunity to catch Minato off-guard, but is it happening? Not sure. Minato can tag every place in the battlefield, so can teleport in an instant everywhere there are his markings. Naruto on the other side can fail to realise one of these markings, which could lead to his defeat. It's funny that some people think that Naruto will win easily. Naruto have to actually think about what he is doing, cuz if he does only one error, it could mean his death. That's why i think this fight could go either way. It depends on certain circumstances. Even the battlefield will be really important to determine the winner