Nano-focusing structures based on hybrid plasmonic waveguides are likely to play a key role in strong nonlinear optical devices. Although the insertion loss is considerable, a significant nonlinear phase shift may be achieved by decreasing the nano-focusing device footprint and careful parameter optimization. Here, we study the Kerr effect in hybrid plasmonic waveguides by analyzing the mode effective area, energy velocity, and insertion loss. Particularly, by utilizing plasmonics to manipulate the effective index and mode similarity, the TM mode is reflected and absorbed, while the TE mode passes through with relatively low propagation loss. By providing a deep understanding of hybrid plasmonic waveguides for nonlinear applications, we indicate pathways for their future optimization.