Yah Carlos is solid but he's comfy with McLaren, good team, a team on the rise and a great relationship with Norris. I don't see him leaving for the clown show at Ferrari, not yet anyway.
Ricciardo is my bet. Solid and proven he can work well with a young hotshot driver. Him and Max had their moments, but for the most part worked well together, and I see him and Lecluck being a solid tandem.
I love Hulk but man, this guy must have spent his childhood smashing mirrors under ladders he just cant catch the podium. If there's a Haas/Aston/Future team opening I could see him there.
Bottas will only be replaced if they want a Vettel/Hamilton tandem to have 10 DWC's between the two, which would be an idiotic decision. Bottas is perfect #2 until George Russell arrives at Merc.
Lewis.... MAYBE one day, but the best shot at #7 is in that merc, ferrari is a strategical tire fire akin only to Mazda in Gr. 3 sat's. The only reason I see Lewis in red is because he got his record championships and wants to drive ferrari for the chance to say he did.