The architecture of 5G networks relies on partial function centralization to reduce operating costs and allow for improved interference management. Nonetheless, partial centralization results in suboptimal operation if the functional split between centralized and distributed functions is not adapted to the time-varying network conditions. Previous work has tackled the problem of selecting the optimal split for fixed conditions, yet it is unclear whether and when dynamic deployments are superior to static ones. In this work, we provide a comprehensive study on the feasibility and profitability of a 5G network featuring a dynamically-adapted functional split. We formulate the selection of this split as a novel optimization problem that combines performance and operating cost into revenue. Moreover, we base on a dedicated cost model to propose multiple adaptation strategies and evaluate them under a wide range of network designs and conditions. Finally, we show that a dynamic functional split may lead to substantially cost reductions (or revenue increases) with respect to static configurations.