I would say from my limited knowledge of that specific part of roman history, Boudiccas rebellion was less a organized resistance against Roman rule and more a large riotous mob moving across southern Britain. Anger against roman power in Britain made manifest through violence. If she was successful, I think you would see something similar to what happened after Popé's revolt in the Pueblo Rebellion, a charismatic leader pushes out a foreign power on a back-to-roots, grassroots violent rebellion but sees their movement quickly fall apart due to infighting. This is, they never founded a new identity, only aggressively reaffirmed a old one, but that same old identity was one that was fiercely against any sort of large overarching organization.
I would imagine there would be a brief period of re-britishization, the removal of roman culture and certainly the slaughter and driving out of actual romans, but then Britain would immediately fall back into tribal confederacies and decentralized rule, to be quickly followed by a massive retaliatory roman invasion. Whether or not the Romans stay in the long run is the larger question. As with Germania, they were defeated, driven out, but then returned, crushed the rebellion (Germanicus), but then largely abandoned the territory anyways. A successful Boudiccas rebellion could affect the trajectory of Roman britain significantly, but it would be after the Romans would have defeated Boudicca regardless.