Mmmm, I hope the good citizens of Blaenau think long and hard about such a commitment. I'm not against NPs and I applaud much of the work they do. There is however a side to such an organisation that does not sit easy. While they encourage certain pastimes and occupations "they" consider acceptable or beneficial, they can be zealous in controlling industrial aspects of the landscape. I'm not advocating a wholesale disregard to what industrial concerns do in NPs but such regions (NPs) also have to sustain a working population and such areas can only support a limited number of park rangers & Yoga teachers 😉
If you look at most of the National Parks in the UK you will see that some of the landscape we are hell bent on preserving emanate directly from the industrial past.
Another often forgotten fact is that there are areas close to or sometimes within NP areas that are to the uninitiated thought to be in them anyway. There's no such thing as a free meal and joining may just bring more disadvantages than apparent gains.
Blaenau to me looks very much part of Snowdonia and I'm sure it can promote itself in the tourism world without the endorsement of the NP. In our part of the world Buxton does very well without being part of the NP.
Quoting from the BBC article "Blaenau Ffestiniog, which is flanked by the Snowdonia National Park, offers a rich industrial and cultural heritage, said a local councillor." Surely that heritage is for the folk of Blaenau to benefit from not the NP who would undoubtedly return the favour by putting onerous planning restrictions on the residents as an example.
The past generations of Blaenau endured hardship, low wages and almost certainly poverty in their lives. Their toil is now the legacy which can be seen today. It may be wishful thinking but someday a use may be found for the slate or there could be a revival in its use as a building material.
What a heritage to squander. We are too fond in this country in casting off our past in haste only to re-invent the wheel sometime later.