A new manager and some investment in key areas will keep them competitive but I think the Barca dynasty of the last 2/3 is over. Puyol, Iniesta and Xavi aren't getting any younger either.
Think Pep has showed his shortcomings here, how much did they spend on Cesc / Alexis? Two players you could argue they don't really need (despite how good Cesc has been).