It's a toss up.
Depending on the final product, critical acclaim could push sales for Britney Jean even without promo, or whatever Britney considers promo these days.
Seeing FF couldn't outsell 4's first week sales, U.S. total sales, and WW total sales with 3 Top 10 singles (that the Army cherishes so deeply), don't think BJ will be able to match FF numbers let alone 4's numbers.
It will be interesting to see how the tables have turned.