It's most likely going to be played in third-person, with first-person visor modes available for more complex targeting like during a boss.
What concerns me is, WHERE'S THE MORPH BALL in that video?
I think it'll be primarily 3rd-person, too, but in 3D or 2.5D? I have to imagine they'd go mostly with 3D, which would be a nice evolution for the series. (I don't want this to be just New Super Mario Bros for DS, but featuring Samus. They can do something like that on DS later if they want).
As for the Morph Ball, I wouldn't worry. Retro nailed that element, so the groundwork is there, and Other M interviews have stressed it'll have all the classic Metroid exploration as well as the action, so that follows that the Morph Ball is an iconic must.