I guess, but usually games will specify the platforms if they are having multiple on PC, I am assuming it is likely that there will be a MacOS and Linux version, but it is being made by another studio, so.
That space-race idea is awesome. They should definitely keep singleplayer and multiplayer separate, with the option in multiplayer to have a public or private server, so you could have up to something like 10 or 15 people playing at one time on a server or just have you and a friend or two playing.
I was just wondering if KSP2 will have either support MacOS at launch, later in the game's life, or even at all. My windows laptop can barely run chrome well, so I am hoping I will be able to play on my iMac!