I can really understand the drive that wants to reinforce national identity through Welsh. My London is a mongrel place so full of confidence that the fact that the English can't afford to live there and it's possible not to hear any English spoken on the street doesn't perhaps matter. But for Wales, in a joined-up world I'd question the wisdom in teaching a fair chunk of the population in a language that has no relevance to that world.
There's an interesting parallel with Catalonia which under Franco was an industrial powerhouse, ahead of Madrid. After his death the region became autonomous and Catalan, almost banned under Franco, became the chosen language (with others). Although not in fact the majority language in daily use it's the language of government etc and is required to be used for all information displayed to the public. One way and another Barcelona lost its appeal to business, which 30 years on is dominated by Madrid. The international companies which came to Spain almost always established in Madrid, language being a key component.
Now the recent election has put secession firmly onto the political agenda. Madrid is going to fight this tooth and nail which is going to impact on any discussions the Scottish Parliament wants to have with the EU on independence. Madrid will probably vote against Scotland being allowed to join the EU simply because of its fight with Catalonia.
The more the world shrinks the more people want to belong to something local and the more the national politicians hate it! Good luck to the Scots and Welsh.