Yes, but for someone looking for a direct train from Scotland to London or vice versa, it would be a very bad thing; if both franchises were run by only one TOC, they would be able to bump the prices up more on both routes, and they would not lose passengers to another TOC, unlike if they only had 1 franchise and bumped the prices up on that, then people would go for the much cheaper option on the other line, and the TOC woud lose customers and money.
I think if both were currently operated by a single TOC, the price rises would have been much steeper than they have been.
We will just have to disagree on this one. Edinburgh - London is already a rail monopoly in terms of direct trains, very few passengers will travel to Glasgow to get to London instead. If you look at passengers on the ECML trains that have left Glasgow only 1 or 2 are ever going beyond Peterborough most are going to Newcastle, York etc. People making that kind of journey hate changing trains.
If they put up the price too much people would fly or use the coach. I think areas such as East Anglia where National Express operate both the trains and coaches would be much worse than one operator having both rail route.
In my ideal world both routes would be operated by the same operator, BR

But I think as most of the UK has no choice put to one operator why should London - Scotland be the only flow that only having one operator is not allowed, why is it OK for London - South Wales to only have one operator? Double standards me thinks and the same arguement applies to South Wales, if they put the prices up to much who can the passengers use instead, it isn't as if they can fly or use the sleeper!
The other thing I suspect Virgin think they can legally challenge the ruling as it is so inconsistent in the logic that why is only London - Scotland protect but London - Kent isn't? Otherwise they would not have bid twice on the ECML franchise. Bidding costs a lot of money so why waste it when you know "legally" you never be allowed to have it. People were saying last time around that as long as they didn't own XC which they don't they would be OK as only London would be effect the majority of destinations would have competition as discussed earlier. Edinburgh - Peterborough for example use XC and EMT!