I wouldn't really read much into that tbh. It's certainly possible he could re-sign with the Blackhawks, but it seemed like he was pretty fed up with where that team is at competitively. Deep in the throws of what looks like it's going to be a very long rebuild. Someone like Patty Kane can also afford to have multiple million dollar mansions in different cities. Treat that Chicago home as one of many, maybe hang out there in the offseason. Or just sell it.
There'd maybe be something to it if he made that purchase right before the deadline when it was clear he was going to end up dealt. But a bunch of months before, in September, before the season even really kicked into gear? There's practically nothing to that. He likely had a very different expectation of how the season was going to go and where he was going to end up. Probably just wanted a nice luxurious place to live while he collected his final Blackhawks paycheques before his salary could feasibly be moved at the deadline.