VlaudTheImpaler
tl;dr
Windows 10 PC demo update (bottom of page):
http://www.forzamotorsport.net/en-us/news/FH3_Demo_Announce
"We know fans are curious about the state of a Windows 10 PC demo for Forza Horizon 3. A standalone Forza Horizon 3 PC demo will be released sometime after launch. We invite all players who are eager to play Forza on PC to try Forza Motorsport 6: Apex, available now in the Windows 10 Store for free. The Windows 10 version of Forza Horizon 3 has been built in lockstep with our learnings from Forza Motorsport 6: Apex, which just released out of Beta last week and added wheel support. Were dedicated to bringing the quality and innovation our fans expect from Forza to the PC, and were confident players will have a fantastic experience with Forza Horizon 3 at launch."
Kudos to them for being upfront about it.
Sad that it can't be here sooner but this means a lot.