That seems like the best way to go, too many great games have unresolved issues, I would hate to see this one go that direction too. But no matter how good the new one is, leaving this one unfinished would be a black mark on your reputation. Look at how good Milfy City is, but then you see that every other game that guy has made was ended before it was done, and now he is taking another hiatus, meaning this game will lilkly end now that he is done with the family stories again, long before all of the promised side characters get any content. No matter what his reasons were, I have no trust at all that he will finish this one either. Being ODC, I hate leaving good things unfinished, no matter how long it takes.
It is also a bit difficult to get too excited about a project I don't know a lot about, especially if it could cut into the one we already love. That said, a good way to get us more excited about the new project, when you get to that point, is to start leaking details. I am sure the more we know, the more we will love it. While I hope this one will not suffer from the new one, I do look forward to seeing what you are planning, and how you plan to make it work.