I never bought the "B-4 could be Data" argument, anyway, for the reason's Christopher
Yes, Data's information and memories were transferred, but reduced to facts and events, rather than experiences. In other words, nothing that actually made Data the "person" into which he had evolved over the years made the transition, as B-4's systems were inferior to those Data possessed. This much was stated in the movie, and to some extent is exactly the scenario Data feared would happen when he faced off against Maddox in "The Measure of A Man."
Now, can B-4 learn and evolve into his own person, perhaps guided to some degree by what Data left him yet still having his own experiences, making his own mistakes, and so on? That remains to be seen.