The cost of the station, back in 2020 was £120m.
I guess the parallel is Bristol Parkway, or more recently Worcestershire Parkway. Bristol was 'out in the wilds' for many years but close to motorways. It was a pretty basic (well ugly basic) station for many years and was incrementally improved to what it is today.
That is a very good analogy. Now Bristol Parkway is arguably too small and in need of work on its various junctions. It is a long way from the Bristol Parkway I first used.
There has to be realism about development. The channels along railways are natural candidates because they have the public transport in place. The South Wales Main Line is even more of an ideal candidate because it has reliefs to allow stopping trains to call at the new stations.
The proposed Cardiff Parkway is not a junction, but it is passed by trains to diverse destinations (Manchester, North Wales, Crewe, Birmingham, London, Bristol and South West) that could call if demand grew. I do believe there will be organic growth rather than a big bang.
It seems there is a virtuous circle for development and that this is the natural extension direction for Cardiff.
One day maybe Cardiff Parkway will be like a new Stockport.