As an airline pilot (and one who formerly worked very recently for the regionals)…this consolidation makes sense.
Mesa retired their CRJ900 fleet as they became an all E175 operation. Republic operates all E-Jets with a ton of E175s for United, and so functionally the onboard product is the exact same, with Mesa just flying for United while Republic flying for the big 3.
Passengers won’t notice any different. Flight attendants wear the same uniforms at both (maybe different wings but nobody’s gonna notice). Pilots probably will have to get used to new SOPs but functionally, it’s the same airplane they’ll probably be flying the same way.
Mesa has been struggling financially for the longest time. Republic seems to know what they’re doing. So this would make sense as a way for Republic to expand (and eliminate a competitor in the process).
Begs the question what will happen to existing and new United Aviate candidates and what the prevailing Union will be (ALPA vs Teamsters). But time will tell.