… use shall only to impose an obligation on the subject of the sentence, as in Acme shall purchase the Shares. A contract can, for better or (usually) worse, articulate obligations in other ways.

.. it’s best to use will only with respect to future contingencies, but there’s nothing uncommon about that. Language of policy relating to future contingencies is an utterly routine component of contract language. Here’s one example: Any attempted transfer of Shares of violation of this agreement will be void. Here’s another: This agreement will terminate if the Market Price falls below $1.00. …