All good points but we not talking LH on a 737, we are talking about whether NAS is burning money. FR and U2 don't do LH.
FR and U2 can survive a shock to aviaton market because they can drop fares and just get cash in, they may be unprofitable for a while but their reserves will cover it.
NAS not in same position because its cash position is tight and losses have to be funded from their cash.
At the moment based on publicly info available they probably 50-50 to be around in 3 years time, odds work in their favour provided economic conditions stay favourable and they get through next 12 months.
An Icelandic volcano scenario like 2010 with a huge jump in Oil prices I would revise that.