Hopefully he goes forward more this year as he doesn't have to baby sit as much for Roberto compared to Dani.
He'll still need to babysit Messi.
No matter how the trio on right side will play (Messi-Rakitic-Roberto), who will babysit whom and who will play slightly more attacking, at the end of the day, this will always be a weaker trio in attacking terms than a Messi-Rakitic-Alves trio, and on larger sample of matches we will just suffer more and create/score less goals from right side, but also less goals in total probably.
Against weaker and average opponents we will be fine.
But in matches where we struggled (in creation) even in the past with Messi-Rakitic-Alves, I really have no idea how we plan to unlock strong opponent's through the right side.
This trio is weaker in general, and since Roberto isn't an offensive treat, opponents will just double man mark Messi (a guy who used to cover for Alves will now let Roberto run freely without a marker and slightly risk with him and cover him only when he gets extremely close to their box, and that player will usually just double mark Messi).
We aren't in the worst Messi-pendencia era anymore, but we still heavily rely on Messi.
So, Lucho will need to find some new ideas probably on the other areas of the pitch where we will need to offer some new attacking options, like Neymar creating more, Iniesta creating more, Denis creating more etc.
If Lucho won't tweak anything and if we'll just play 100% the same, except that we will have Roberto instead of Alves, then our attacking game will suffer on a lot of levels on larger samples.
It isn't just a simple new guy for an older guy substitution (1 for 1 sub).
It creates a domino effect all over the field:
1. Roberto attacks less than Alves
=> because of that Messi is marked more than before
=> because of that Messi needs to drop deeper to midfield
=> because of that we are lacking width
=> we attack too much through the middle, and that way we are easier to neutralize
=> also, since Messi is double marked, he will score less and create less
=> that means less goals from Messi, but also less shots on goal for Neymar and Suarez who rely heavily on Messi's distribution
=> that could easily mean less clear chances for Barca in general, less goals, slightly more draws against midtable teams
But again, it doesn't need to be the end of the world, as long as Lucho will find a new solution and if some other players will take more responsibility to neutralize a loss of Messi-Rakitic-Alves trio from the right side.