If the APA ratifies the TA, then the 190/195 will be mainline (Group 1) at AA. If AA imposes the April demand (term sheet), then the 190 could, as you pointed out, be flown at Eagle/express if the total seats were 88 or fewer. 88 shouldn't be a problem if it's configured with four rows of F (12 seats).I stand corrected on these E190's not coming home - I must have been playing hookey when they were sold to Republiic.
At the risk of being wrong again, I believe Republic is the only U.S. based regional operator that flies the 190 since Frontier is the only mainline carrier whose scope allows planes with that much capacity. USX doesn't operate any for US, US and B6 fly them as mainline, and with enough FC seats AA may be able to operate them as express depending on the final agreement with the APA but it would take enough FC seats to reduce total capacity to 88.
As an aside, jetBlue's top FO rate on the 190 of $100/hr is a dollar less than the US Captain rate of $101. From my perspective, that's a lot of nose cutting and face spiting. Letting emotions rule can be very costly.