Just to add a little bit about why the line was kept open. despite Beeching. It was needed for the Trawsfynydd nuclear power station, now life expired and being decommissioned. But the original GWR line from Bala, which passed Trawsfynydd, terminated at a station towards the south of Blaenau Ffestiniog, while the LMS line from Llandudno Junction terminated at the north of the town. Amazingly, the gap was bridged only by the narrow gauge Ffestiniog, and while the upper parts of that remained closed in the 1960s, its track was lifted to make way for a through link, so that trains from the north could get to Trawsfynydd. That was a lot more practicable than routing trains from Sellafield through Bala, but what really forced the issue was the construction of the Llyn Celyn reservoir. A diversion round that would have been possible, but expensive and with fairly severe gradients, while the way through central Blaenau Ffestiniog was simple.
I remember visiting Blaenau Ffestiniog around 1962 and being quite amazed by the two unconnected BR stations, and the notice on the Ffestiniog station, complete with steam loco on display outside, proclaiming that train services were "temporarily suspended". They really did mean temporarily, although it took many years for them to get back to the new combined station.
I also walked across the somewhat derelict bridge over the river Glaslyn south of Beddgelert, and imagined trains running there, and through the streets of Porthmadog, again. Happily, that will be happening very soon now. But in those days Caernarfon had a main line station, now gone.
I think that tourism will prevent any further closures. Whether anything else, such as Caernarfon to Bangor, will be re-opened (not easy, but there are plans for redeveloping the old Firestone factory adjacent to the line, which may influence the outcome), remains to be seen, but it may well be that the nuclear industry is responsible for keeping at least one line open, for long enough for the influence of Beeching to be no longer relevant.
As the line between Blaenau Ffestiniog and Llandudno Junction has had severe problems in recent years, parts having been washed away several times due to floods, extensive usage by heavy freight trains carrying slate waste may be just the thing to make properly repairing and upgrading it financially viable. The passenger service alone could never justify major investment, so it may well be saved again by an industrial user. I certainly hope so.