Yep this is what I was thinking (re Preston) also - Manchester to Edinburgh would be hourly.Im all for it as it simplifies crew aswell. Avanti won't need an Edinburgh base, nor will TPE need a Glasgow base. Plus TPE already operate ECML services out of Edinburgh.
However I think most TPE services in Scotland are crewed by Glasgow, even the ECML ones as I don't think Edinburgh has a crew base.
Another solve for the Glasgow, if paths were tight - could be a split at Oxenholme with an hourly Windermere (wired). Which then also runs to on Glasgow.
I'd cut the Barrow back to either Lancaster or Preston - or maybe to Liverpool instead and create another regional service.
Or the Liverpool-Glasgow paths have Manchester sections join them, and Manchester-Glasgow is only those. Something has to give. Liverpool has no Edinburgh really (the TPE routing is absurd for that journey) - so it's not all loss.