I don't know what effect welsh-language tv is having other than giving the massive some REALLY boring soap operas. But the Welsh language is definitely alive and well. About half of my co-workers and the residents at the old age home I work in speak Welsh. All my co-workers' children speak it as it is compulsory in schools nowadays (as opposed to in the past when kids were severely punished for speaking it in school). Overall I think about 25% of people in Wales speak Welsh and that percentage is bound to grow steadily as kids grow up speaking it.
Wales, especially South Wales, contains some of the poorest areas in Europe, it also has the highest rate of teenage pregnancies in Europe (I guess it gets kinda boring on the cold winter nights, not much else to do but...) There are defintely parts of Cymru (Wales) which would be defined as third world in terms of income, access to medical care, etc. But as far as the language is concerned, Wales is not in trouble in that regard, the Welsh language is growing not diminishing.