Fullbacks score goals very rarely. Even if they can shoot or finish well. Simply not their job.
If Valverde carries on with these tactics Semedo will most likely not be bombing on in final third too often.
The width on the right will be taken more by a wide player and Semedo will be more reserved in getting forward than Alba on other side who is more or less a wing back.
Similar to the way it used to be with Alves being like a winger and Abidal more reserved think is way it will go for a while yet.
I think its better that Alba become the more attacking wing back bcos it simply favors Messi's left foot. Messi has scored more from the overlapping runs on the left (Neymar, Alba). However, in terms of linking up, 1-2s, he's better with Alves.
However, if Dembele were to play RW, Alba will have to take up the attacking role that Neymar left. Suarez could help out Alba but he doesnt have the speed so Alba will throw himself forward more. Defensively the left side will be compromised. Thats what Im worried abt.