I don’t think there’s going to be any great changes to tax and duty, particularly on cars already registered. Not so long ago the government was essentially promoting diesel as they tax on co2, and diesels generally have low co2.
All talk of scrappage schemes seems to be only if you trade against a zero emission car, i.e fully electric. Can’t see the uptake being high enough to significantly affect diesel residuals.
Edit. Urban tax might apply, but I can see towns applying that as much to petrol cars aswell as diesel. Basically keep cars out of city centre.
The media as usual appear to be hyping up the situation to make stories.