Norwegian are an interesting operation. No one has made long haul low cost work, ORK-BOS is a long thin route, operating it with the 737MAX is unusual but potentially revolutionary. I understand why people in the industry are concerned about the terms and conditions at Norwegian, and a number of their associated companies. There are some potential safety concerns with third party crew providers at Norwegian. Although ininderstad those crew providers are common throughout the industry.
I do hope Norwegian make this work. I don't think it's certain that Norwegian will harm Aer Lingus, they seem to do just fine against Ryanair on short haul routes.