I contacted Channel 4 through their website, and asked whether they'd have their own commentary team in 2019, or would take Sky-produced highlights. They emailed a reply, saying:
Thank you for contacting Channel 4 Viewer Enquiries regarding Channel 4: F1.
We appreciate you writing in regarding your interest in the programme.
Unfortunately we have no information regarding our highlights package as yet. However, your comments have been noted and logged for the attention of those responsible for our programming.
So now we know that we don't know. Nevertheless, I was impressed that it was possible to contact Channel 4 so easily, and that they replied quickly. Very different from most organisations.
All that means is that the person looking after responding to contacts of this type (if, indeed, there is a person, as opposed to a simple text analysis program that fires off stock responses based on keywords present in the text) does not know and either cannot find out, does not have a mandate to find out or simply cannot be bothered to find out.