In La Liga I agree but not in the CL, they will struggle against big teams in CL without Messi, just see in the future.
against which teams? midtable La Liga teams yes but when the big guns in CL await, Barca will have big problems without Messi. It's true that Barca this year seems to be less Messi dependent, but as I said in big games they still need Messi more than other big clubs need their star players, Barca in CL QF or Semi without Messi is half of a team.