I could see the E170/175 fitting in fairly well with the sorts of routes Eastern operate and this should allow them to fly longer/more popular routes while the high fares should help them turn a profit even if loads aren't too good.
A319 seems like 2 steps too far for who are basically a small regional airline unless they are planning some long oil related routes from ABZ. E190/195 again seems a little large for an airline like Eastern and lack the range of the A319 so would struggle with any 'oil routes' if they were even ever to happen.