In my opinion keeping the older 700s with the bigger engines was their biggest mistake, and no matter what way you play it, the EJet whilst nice to ride on has been a mistake. Yes there is a place for a 100 seater in Oz, but all the ones that work in OZ do so because they are old, cheap and depreciated. The E-Jet was brand new - thus expensive to either buy or lease, and doesn't burn a heap less fuel than the 737-700. The 700 also has the potential to carry 30 odd more pax, and you don't need a whole new set of crew to fly it, FAs, GSE as well as parts etc.
The whole Jet vs T/Prop discussion is a null point - ask your average friend without any aviation knowledge when they book on VA or QF website to say ROK if they know they had booked on an ATR/737 or Q400, no one would even know.
E-jet is also apparently experiencing increased PDAs, engine wear and engineering issues as they age. By all accounts American, Air Canada are dumping theirs, and JetBlue is also looking and removing them as well. Crew love it, pax love it, but the accountants (and engineers) hate the thing. Engineers say
Every
Mechanical
Breakdown
Requires
An
Electrical
Reset
Couple of old articles about the problems Jetblue have had with them.
JetBlue CEO Laments Embraer 190 Costs | Commercial Aviation content from Aviation Week
https://www.bloomberg.com/news/artic...g-cost-problem