No. This definitely does not preclude more than one option from an FDA regulatory point of view. The iCGM is out there and a done deal. So we can assume certain things about the iPump based on the iCGM but realistically there is a whole lot of speculation until it (iPump) is done and published.
The FDA specifically wants and is encouraging interoperability.
Tandem has publicly stated that in addition to the FDA approvals, there is also the business relationship required. As well, Tandem said that the near future (which includes the t:sport) does not include end-user ability to plug-n-play components as they desire. (Paraphrased - although I am sure I could find the exact quote.)
So from the Tandem point of view, there does not seem to be a near-term option in terms of the algorithm. It is currently Basal-IQ (developed in-house by Tandem) and will soon (Summer of 2019) be Control-IQ (licensed technology from TypeZero which is now part of Dexcom). However on the other side of thinking, Tidepool has stated they are in discussions with pump manufacturers in regards to the iPump (without being specific as to which pump companies) which would certainly seem to imply Tandem. During initial phases of partnerships between companies, I am sure that various forms of NDAs are quite common. So there definitely could be something going on which is not public information.
In terms of mixing and matching, I would think swapping out one iCGM for another (like maybe Dexcom for Senseonics) would be an easier place to start. That concept (from a regulatory point of view) appears to be fully in place by the current FDA standards in regards to the iCGM. Although until another company (in addition to Dexcom) has an FDA approved iCGM then it remains speculation.