As I said, I can't find anything that adapts from USB Type-C to Firewire. The best I can find is USB Type-A to Firewire which you can then possibly adapt to USB Type-C but the more adapters you throw into the chain, the bigger change you might run into an issue.
The other side is the software needs to be able to see the device on the Thunderbolt interface and if it is too old it might not support it.
I guess the only way to find out for sure is when you get a new computer.