Sané, Sterling and G.J are definitely the future of the club, but they are also more or less cut from the same cloth. Fast, tricky, but not necessarily at their best when playing in a tight area with no space. Nolito comes in as a great squad player because he is great at the combination play around the edge of the box that gets a breakthrough in those games when the opposition is not trying to play positively.
He's not doing great at the moment, possibly he's having to come to terms with a squad role after starting so much at Celta.
Roberts has the potential to be both of those, as he offers a level of close control that's really unparalleled - he will beat 3 men in a phonebox - but he is very small and very raw when considering we've already got 3 players 22 or under in that position.
I'd certainly be happy if we went into next season with Stelring, Roberts, Jesus, Sané and Nolito as the wide options though.