Possibly.
However, Rubio's going to get crushed everywhere else in South Florida (Demings will dominate in Broward and Palm Beach), and the I-4 Corridor should be a bunch of easy Demings victories as well, so Demings should still have a chance, even if she loses Miami-Dade.
I don’t think Val Demings has too much of a chance for victory. Maybe at best she loses 51-47 or 52-46. Marco Rubio is an extremely popular Senator and has a relatable base with Cuban Americans as well as extremist Trump voters.