The crayonista route is IIRC to run over fabian way as an elevated route then to join the station over Parc Tawe retail park and the strand which would need to be flattened. I'd be curious how a figure of £1bn was arrived at for the complete metro. I would have thought the cost of the 10km of new track alone would be similar to electrifying Swansea > Cardiff to the amount of elevated running and compulsory purchase needed to deliver.