I can see Florida drafting MacKinnon at #1 overall. He seems like a safer pick than Drouin, as he's been slated to go 1st overall for a couple years now. His production in the playoffs has been on pace with Drouin and his regular season numbers would undoubtedly have been better had he not been injured.
Also, Florida already drafted a high risk, high reward type player with a similar skill set in Huberdeau, so I think MacKinnon makes more sense than Drouin as his game is more about balance, puck control and vision, where as Drouin's is deking, creativity and vision. In theory, the two centers (Hub and MacKinnon) would complement each other very, very well, similar to how MacKinnon and Drouin have meshed at Halifax.