Here’s a suggestion I’m surprised hasn’t happened yet.
Since High Fidelity is already on Steam, maybe HF could ask Valve for permission to include the playable characters from TF2 in High Fidelity’s marketplace as free avatars.
Thousands of people already create machinima with these characters in Garry’s Mod and Source Filmmaker. Those people could all potentially become High Fidelity users too.
I think the Fuse on Steam already has the TF2 characters included, but it’d be much easier if the models were already on the HF marketplace so people don’t have to fiddle with Fuse. The Steam version is outdated and didn’t even work right last time I tried it.