Completely different roles in the team? If Root was to get in the T20 team it would be at the expense of Malan imo as the role of anchor keeping the innings together, Livingstone and Moeen are in that team to come in and go at 300+ strike rate, sometimes they'll look a world beater, sometimes they'll look daft but more often than that they'll hit a quick 25.
Livingstone had a great world cup last winter and a was in the IPL TOTY, with Morgan stepping down and Stokes probably stepping away he seems the natural fit to come in there - the pressure will be on but he's shown enough over the past 12 months that he can do it I think.