If those folks could just pick up a cheap Areo subscription
There won't be any such thing as a cheap Aereo subscription though.
Once Aereo starts paying broadcasters their requested fees their product will cost as much as any basic cable subscription, because the bulk of the cost of the service is the content, and Aereo needs to cover service costs and make a profit on top of that. Aereo's entire business plan (from a revenue standpoint) was based on using OTA provisions to cut out the content costs, making their only cost the service itself. The SCOTUS ruling has put an end to that.
Aereo can "win" in as much as they may be able to force the networks to negotiate with them, but that's it. And TFS got something very wrong here: the 1996 cable reforms mean that the rates are de facto set by the networks and not the government. The older statutory royalties provisions will not apply here; for various reasons this is not how business is done today, and every last cable company is now paying rates set by negotiations.
Consequently Aereo's backup plan of simply paying less than the cable companies for the same content will also fall flat on its face. They are going to pay full price, the same as anyone else, and they're going to need to find a way to structure their business around it to make it viable. Otherwise, to invoke XKCD, this is the copyright equivalent of thinking you can protect a laptop from the government with encryption. Aereo will simply get wrenched; this isn't a battle that can be won with legal tricks, as evidenced by the SCOTUS ruling.