The 100 seat aircraft market is very important to blue. The 190 style aircraft isn't going anywhere IMO.
That said.....SCOPE.
Look at Alaska as a perfect example of what not to do. Smaller than us (2000ish pilots I believe) and they have Skywest doing their flying on the 175. That is absolutely unacceptable IMO and exactly why scope is so important for us. I used to watch Skywest 175s pull into the ramp after a 3hr+ flight. Things like MKE-SEA. Those should be 737s with Alaska crews behind the controls, instead they're being operated by a cheap third party.
I don't care if JB wants to pay me $400/hr to fly as an FO in the 190, if there is bad scope language, my vote will be a big fat NO. Those are JetBlue pilot jobs on the line. If the ticket says JetBlue, it should be operated by a JetBlue ALPA employee. Same with paint shop and delivery flights. If a jetblue aircraft is taking to the sky, a JetBlue pilot needs to be at the controls.