Just imagine how good he will become once he gets to play many games in a row in a set position. That's what he deserves. I dont know anyone who is able to slot so seamlessly into the team without proper match fitness or hardly ever having played the various positions he plays.
I don't think that he will ever get a starting spot in Barca.
At least not in the upcoming 3-4-5 years.
Dr: he would have to wait for Alves to retire, and since we have Vidal, I don't see a starting spot here for him. Just a squad player.
Cdm: Busi will play for years (if he doesn't get a serious injury). No room here again.
Cm: Rakitic, Iniesta, Arda. At least 2 of them would have to retire/get sold for Roberto to get a starting spot. Plus, we couldn't buy any other Cm (Gundogan, Pogba), plus all younger midfielders should stay below Roberto in their future development (Rafinha, Suarez, Samper, xx...)
Rw: Messi. The end of story.
I think that Roberto will be beloved part of our squad, who can (and will) always jump in on multiple positions when needed.
He will never be a starter, but he will be very important part of the squad who will probably play 20-25-30 matches in every season (rotations, injuries, cards).
Not good enough for the first team, but very close to it, and useful on multiple positions.
A guy who will be the first choice (or better to say: the 2nd choice) for more or less every position.
Something like Guti in Galacticos.
Galacticos took his place, but whenever someone was injured or tired, he was a sub for all positions.
And Roberto is even more versatile.
Gabri Garcia was a similar player for us 10-15 years ago.
Never good enough for the first team, but good awesome and versatile squad player, who in the end played 130 matches in 7 Seasons with Barca.
Gabri played at similar positions as Roberto:
-- as an attacking Rb, as a Cdm, as a Cm, as a Amc (if needed), plus he could cover all Rw positions in any 343, 433, 442 and 451 formation back then.
So, imo, Roberto will be Gabri of this era.
There aren't too many videos with Gabri from that era, so I will post this one: