This project is in the early stages of development by Network Rail and it could go ahead, dependent on funding.
In his budget statement, Swinney revealed that ministers are trying to fund the Borders railway and the Edinburgh - Glasgow improvement not through direct capital spend, but through Network Rail borrowing against it's assets base in Scotland.
I have no idea if this funding model is feasible or not. Presumably the debt would be recouped through track access charges to train operators?
So I imagine any enhancement to the Inverness line would depend upon a similar funding model.
In contrast, they are not funding the road building programme (including the ludicrous second Forth bridge white elephant) through borrowing, but through raiding the revenue funding account! Public services are being cut to fund bypasses and an unnecessary bridge.
Tells you all you need to know about the SNP's real priorities.