I cannot see any 'academic' needing to travel between Oxford and Cambridge- they even deny the existence of each other
Don's are 'experts and are more likely to relate to the USA, and by Zoom or Skype or Teams or via a conference in Seoul. So maybe a trip to Heathrow (via Old Oak in due course?), or Oxford London Airport for a private jet, once a month, rather short of 2tph.
As regards tourists, how many old stone quads can one take? A visitor to Oxford is far more likely to visit Bicester Village (and back to London, Marylebone maybe, having travelled from China for their dozen pairs of shoes in a new suitcase, or travel on to Stratford on Avon for the afternoon and theatre before returning to London. I don't know about Cambridge; I have lived in Oxford!! I took the X5 Oxford-Cambridge one day, it felt like all day. Maybe MK the centre of England's Economic Heartland will generate 'business' (or tourism?)