Will DROP TABLE of an empty table with a large tablespace file cause a long lock?
What version of MySQL are you using?  

I'd do a RENAME table then delete rows in chunks (something like DELETE FROM TABLE LIMIT 5000; in a loop) once it's empty you should be able to drop it.

Adjust the LIMIT 5000 up or down depending on how long that operation takes, slave replication falls behind, or it's affecting other queries performance.

If it's an empty table then no, it shouldn't cause a long lock.