Europe on the edge of catastrophe?

With the WTC, people would have agreed that if it went down there would be many deaths (and the idea it'd be attacked was also not new, because it was bombed in 1993). Here, I'm not challenging the possibility of an attack, I'm saying that your idea of the consequences is absurd. The difference is that estimating the consequences of losing generating stations is much, much easier than estimating probabilities. Saying "a few days of blackout would have an unparalleled impact on installations and economy" -- it would have an impact, but key uses would have backup generators. I haven't gotten into the likelihood (or not) of destroying transformers (for starters, each reactor seems to generally have an independent transformer set, so there are 58 you'd have to disrupt instead of 15).

Also, you seem to be saying "People wouldn't have believed this could happen, and it did, so this should also be taken seriously". It doesn't work like that. Before you can credibly claim Europe is "on the edge of catastrophe", you have to make a decent argument yourself; you don't get the benefit of the doubt, and extraordinary claims require extraordinary evidence.