We ran a drill a couple of weeks back where everybody worked from home to ensure that if we have to close our office we are able to continue working (assuming we're not ill, of course). This was really just to shake out any issues.
Fortunately, since most of us already work remotely for at least some of the time we didn't have any significant issues.
We are in a similar situation. 99% of the time everyone is working remote so we don't even really think about this stuff anymore. Our company has been operating like this for nearly a decade. There is a core group that works at a physical office, but they also have the ability to work remote for an indefinite period of time if the need arises.
Distributed/remote companies are amazing for handling disaster scenarios like this. Hurricanes, floods, pandemics, zombies, you name it. We usually just work right through it.
That's proactive thinking, good job. We're looking at the maximum user limits of our hardware and licenses and expect to buy some more licenses for the VPN appliance.
Fortunately, since most of us already work remotely for at least some of the time we didn't have any significant issues.
Beyond that, nothing really.