A lot of people will tell you that 128GB is too much. The thought here is that your flights are short (limited by battery times) and you might be better off changing smaller cards once per battery or two, so that you have at least have that much video saved in case you crash. I personally don't like to plan for crashing (I will have more to worry about than lost footage if that happens).
I think 128GB is okay, especially if you turn on the option on to save DNGs for hyperlapse and panos. But I do always have more than one of them. I carry a couple of 128s and a couple of 64s.
I doubt you will need a larger card. If you travel, you should consider carrying backup storage drives to dump your cards to, so you can format and use continually.
Does DJI no longer supply a list of card types to use? I agree with Cyborg that the Extreme Pro is rated pretty high, U3, V30 (made for 4K video).
Chris