Someone told me that there were rumors of the E170s going to American Eagle. If that were the case, the CRJ900 would probably be outfitted with 70 seats a replacement. Also, I think Mesa has grounded some E175s, which could be operated by another carrier (CommuteAir has added the type). If that were the case, it would all make sense!
I feel like a spruced up CRJ-900 would be nicer than the E170, especially if it operated with 70 seats. I imagine we would have 10 or 12 F seats which is better than 6!
Time will tell.