Sounds nice but I guess the question is *what* you'd spend the money on.
You could insist on a token number of cheap "Exeter to Glasgow" tickets each day (sold twelve weeks in advance etc etc), as a headline grabbing way of trying to distract from the fact that people in Devon face a much longer and much more expensive long distance journeys - but there's very little spare capacity on XC services, so I can't see any fare reductions happening.
You could invest in additional trains, but what? HSTs clearly struggle to match Voyager timings, and there's no space in the timetable to add an extra few minutes here and there (whilst I'd be happy with XC becoming a 100mph railway, if it meant it was much easier to procure additional stock, you'd need to rip up the whole national timetable to accommodate this).
The Avanti Voyagers and the EMR Meridians are spoken for (for the next couple of years), so that'd be hard to get.
802s (or equivalent)? Sounds good, but it'd be a drop in the ocean for XC, unless you rejig the timetables (e.g. the northbound Bournemouth - Manchester service becomes a southbound Manchester - Exeter service, so you'd need to consider spreading any new trains very thinly amongst the network (and then that'd mean training various depots/staff on maintenance/ knowledge). Say the answer is a fleet of seven/eight coach "802"s to run all Edinburgh - Plymouth services (inc Aberdeen/ Glasgow/ Penzance etc) - that'd be knocking on thirty trains... so hundreds of millions of pounds - whilst I'd love to see it, I can't see the Government stumping up those kind of sums - they probably just want some kind of sticking plaster to give some reassuring publicity to affected fliers and give the impression that they are "listening" to the concerns of people unable to take the budget flights any more.
The only bit of XC it'd be "easy" to add additional capacity to would be the ex-Central Trains routes (since most 100mph DMUs could be cascaded there), but these are of no relevance to Flybe passengers.