The situation is analogous to Christians in the Middle East, where one finds a range of conflicting conceptions of identity from Arabism (common among Melkites and Antiochian Greek Orthodox) to Aramaean nationalism (e.g., the Syriac Orthodox) to Assyrian nationalism (mainly the Assyrian Church of the East). This has partly been responsible for preventing the formation of a viable Christian polity in the region.
Interestingly, some Berber activists are keen to launch an effort to convince the rest of the Libyan population that they are in fact all Berbers.
Ultimately, this enterprise is unlikely to gain much ground. While it is true that Berbers inhabited North Africa prior to the Arab conquests, and that strictly speaking the Libyan Arabs are mostly just an Arabized population, the fact is that Arabization (especially in tandem with Islamization) has become a key foundation of Arab identity. In Egypt, an Arabist conception of identity has prevailed among the Muslim population over the Pharaonism promoted by the liberal intellectual Taha Husayn.
In any case, how far back in history would these Berber activists like to go, if the argument focuses on genetics? After all, North Africa has seen a degree of mixing of ethnic groups, including the East Germanic tribe known as the Vandals, who established a kingdom around Carthage in the Fifth Century as the Western Roman Empire declined.
To round off, it is worth noting the recent announcement by the NTC banning parties based on religion, tribe, and ethnicity. This prohibition is unlikely to apply to the Muslim Brotherhood and other Islamist parties at least on the ground level given the NTC’s dalliances with Islamism, but it will almost certainly apply to any parties claiming to stand for Berber interests, since the Amazigh have already been excluded from interim ministerial posts.
In short, this confirms that the emerging picture appears to be one of political rather than cultural marginalization for Libya’s Berbers.