I don't see how you're comparing like with like here, even with your example of Augsburg Airlines. It folded after LH ceased cooperation due to cost-cutting, LH merged its wholly owned assets (nearly all of Augsburg's fleet) into CityLine which made perfect sense.
Also your examples of Aer Lingus Commuter and CityJet, both operate(d) less than economically viable fleets and are/were fully funded by their associated airline/owner e.g. Aer Lingus funded Commuter and Air France/KLM fund CityJet the latter for sale. Aer Lingus Regional is costing Aer Lingus nothing its making them money through the franchise fee, Aer Lingus are investing over €10m in this new fleet deal, it's clear they're committed and most definitely for the next 10 years.