Package Control in 2018 cost around $1,000 to run the server. Opting into Linode's backup plan will raise the cost to probably around $1,230 for 2019. I will likely start going over the 8TB limit for bandwidth in the next month or so, so a realistic projection of costs for 2019 will be $1,300.
Currently there is no plan to transfer the project to Sublime HQ. If I get to the point where I can realistically no longer maintain the server, there would be discussion about community involvement vs Sublime HQ. Ultimately that would probably require some changes due to privacy concerns. Currently I am the only individual who has access to the server and the information.
All that to say, I currently basically maintain the server and do some light work on the code base. @FichteFoll and @ThomSmith do a ton of day-to-day work on the primary channel, reviewing packages and giving users feedback.
All parts of Package Control, the website and default channel are open source, but that doesn't really affect the operational costs of keeping the default channel server running.