How can I lock down an old wordpress install I don’t intend to update?

I am starting a new wordpress blog, and no longer updating an old one.
The old one still gets 400-500 hits a day, so I would like to keep it up for archival purposes, as people still link to its posts.
Obviously there is the problem that wordpress and plugins will be updated, and I have no desire to maintain it.
How can I lock the installation of wordpress down so I don’t need to maintain it?
I have seen someone suggest making a static version, which sounds like alot of work. A more reasonable solution I thought of was to disable write access to the database at the database user level. I’m fine with disabling comments from now on.