Okay we know Ricciardo is probably the man in demand right now by all three teams
Sainz or Gasly would get promoted to Red Bull but neither have made a strong enough case this season yet . Gasly blotted all his good work in Bahrain with a poor weekend in China, whilst Sainz is just a shade slower than Hulkenburg at Renault
Ferrari apart from Ricciardo and LeClerc who is still learning might want to think about the following options
Perez- probably good for Vettel in that he is not that fastest and he brings in good sponsorshop
Giovinazzi - his development work might be a key in getting ahead of LeClerc
Magnussen - he seems to have find his form this season over Grosjean with some impressive performances and the Ferrari link to Haas might be a case to promote him. He is back to the K Mag of 2014 now
Grosjean - at 32 this might well be his last chance to get a top seat, overlooked by Ferrari so there is something that they are unsure about to promote him to the team. Being outperformed by his teammate is not helping his cause
Hulkenburg - so far impressive in leading Renault and outperforming Sainz and there maybe a strong case to consider him but he has been rejected in the past by Ferrari which is a shame because he appears to be approaching his peak
Kyvat - unless there are some powerful Russian backers behind him ,I don't see him being promoted