Thats the hard part I don't know anyone who plays this game. I just hope more people will start playing online when the game is released. Otherwise the money I spend on this game can be considered a donation to the developers cause I like their work and I really hope they will make a part two very soon.
Sins is a great game for online multiplayer PvP, but sadly it's an unknown gem. The game has always had low player counts for online multiplayer but there are normally several 4v4 and 5v5 games every day on the Diplomacy expansion. I've even played in three 5-on-5 games on the Beta and I haven't spent much time there. Presumably the final release of Rebellion will be at least as popular for PvP as the Diplomacy expansion is right now. So, in all likelihood you'll eventually receive some value for your money.
It's far too early to say much about what the final release of Rebellion will be like. The current online multiplayer player counts on the Diplomacy expansion were negatively affected by technical problems that the original "Vanilla" game had early on in 2008 and also by the game's exclusive availability on Impulse (when the Entrenchment expansion was released). Those problems have long-since been corrected. Also, Sins was not available on Steam until the Diplomacy expansion was released.
I really do hope that Stardock figures out a way to market Rebellion to the RTS online multiplayer PvP crowd. I really do get the sense that most of the people who play RTS PvP know almost nothing about Sins and have no idea how great it is.