I see where this topic came from now 
That sounds like a cool concept indeed!
The issue I see (hopefully not foreshadowing here) is it might be hard to have a player-base consisting of people being able to assemble a 4-person party, without the game being successful. And it might be hard to make a successful game without a player-base. So it’s a chicken-and-egg problem.
Even for massively popular games like It Takes Two, where you need only a 2-person party, there are so many posts on the Internet from people asking if it can be played as a single-player (it can’t). They can afford to lose some players, because it’s so popular, but can you afford it?
Do you have some ideas already on how to mitigate it?
Don’t let it discourage you, I’m sure you’ll figure something out.
I’ll be following the progress nonetheless, looking forward to seeing the updates