I honestly dont think it matters much what Lewis or Vettel think. Hamilton is probably out in 2 years. A driver like Leclerc could be the next star for years to come. If they dont grab him now, he will be surely contractually binded for at least 3 years. Could they get him in 3? Who knows.
Anyway, i dont think they could buy him out. They might offer, so i think Ferrari will bite the bullet and put him alongside Vettel in place of Kimi.