Don't think anyone will be doing the whole thing end to end! The reliability will be horrendous though, especially as it's not even overnight. Must be the longest domestic coach route time-wise in the UK? Good spot with the article, helped with...
Had a look through the new timetable on the booking engine and got it into a spreadsheet, linked
here (excludes M4 services). The press release is broadly true, but overall it looks as though there's as many cutbacks as improvements - Oxford and Reading in particular lose out, and there's pretty drastic trims to Monday-Thursday services. And some of the new routes are rather bizarre - I assumed Dumfries and Berwick would be on the way to somewhere bigger, but they are both start points. Maybe something to do with new contractors? Dumfries in particular is peculiar - two a day to London leaving at basically the same time, but with one going via the East Coast and one via the West. Fundamentally though my main criticism of this is how short the notice is - I only had one trip booked which was easy enough to alter, but had this been earlier in the year I could have been really screwed over with the M81 cancellation.
Can't say the spreadsheet will be 100% accurate, please comment on it if anything's off.