Dyfed was replaced by Carmarthenshire, Pembrokeshire and Cardiganshire decades ago. Haverfordwest is the county town of Pembrokeshire and has a train service.Regarding the Manchester - Bangor (Gwynedd), could this be extended to a reopened Caernarfon?
This would then leave Mold being the sole remaining county town (Clwyd) that does not have a railway. Carmarthen (Dyfed), Swansea/Abertawe (West Glamorgan), Cardiff (both Mid Glamorgan and South Glamorgan), Newport (Gwent), and Llandrindod Wells (Powys) are county towns of Wales that are presently connected to the railway network.