As the October 31st extension deadline approaches and we wait to see whether the Thunder and James Harden can work out a long-term deal, it seems rival suitors are already surfacing in the event that Harden reaches restricted free agency. According to Marc Stein of ESPN.com (via Twitter), the Rockets and Mavericks are "huge Harden fans" and are candidates to sign him to a loaded offer sheet next summer.
Thunder GM Sam Presti talked about a potential extension for Harden earlier this week, and his comments suggested that it won't be easy to complete a deal, with compromises required on both sides. As Stein tweets, Harden is a "virtual lock" to receive a max offer sheet in restricted free agency, so he'd likely be accepting a discount if he signed an extension for anything less than that.
Unlike Oklahoma City, the Rockets and Mavericks are both in position to clear a good deal of cap space for next summer's free agent period. Houston has Kevin Martin's $12.44MM contract, among others, coming off its books, while many of the Mavs' summer acquisitions are on expiring deals. Both teams, along with the Suns and others, could be in competition for Harden's services if he becomes a free agent, though the Thunder would still have the right to match any offers.
If Oklahoma City becomes convinced that keeping Harden is impossible, the team could also entertain trade offers prior to this year's deadline, but I'd be shocked if Presti broke up the defending Western Conference champs. Stein confirms that a trade isn't in the cards at this point, tweeting that the Thunder "so far, won't entertain such thoughts."