There are several ways to share access to a Windows PC across the internet, some like remote desktop and the remote assistance services are built into Windows. But none of them are anything like 'real time' enough for people to work on a remote DAW as if they're both sitting at the same PC on an 802.11ac or gigabit LAN, never mind the internet. Multi-player games work across the net, but they are very different things to a DAW. For a start, fhe processing load is spread across all the PCs involved as each runs its own copy of the game, while you'd need one copy of Sonar to handle everything.
Opening up a router and PC firewall to receive incoming logons that allow control of the PC from the internet also comes with some very serious security risks unless the connection is only allowed via a secure VPN with strong security, and even then might still be vulnerable. There are huge malicious botnets that spend 24 hours a day trawling for open ports that allow remote access and if one is found it will come under continuous automated attack.
And if the internet acccounts involved have upload/download data limits multi-track audio can eat into the allowance very quickly indeed, it's a lot of data and every time the project is played the audio data will get streamed.