SQLAlchemy: Will session queries still work after a commit?

Short answer: Yes.
Long answer: Please read Using the Session and also the Managing Transactions part of it.

As @van already pointed out the answer is yes, however here is the explanation based on the sqlalchemy documentation:

When the transactional state is completed after a rollback or commit (i.e. session.rollback() or session.commit(), the Session releases all Transaction and Connection resources, and goes back to the “begin” state, which will again invoke new Connection and Transaction objects as new requests to emit SQL statements are received.