It's no secret that Xiaomi is working on a succesor to its widely successful Mi Band, considering its already been leaked by their CEO.
Right now I'm a bit on the fence about buying the Mi Band 2 if the addition of a screen is the only thing it has to offer. At the moment, the Gear Fit or Gear Fit 2 is a better fit for me considering that it has a built-in music player which is something that I need for my runs and walks.
I doubt that the addition of a 4GB memory to the Mi Band 2 would raise the price of the Mi Band 2 by that much considering the number of fitness bands with these functionality within the $20-$40 price range. I've got my fingers crossed for a built-in music player with hope that Xiaomi nails it for me.