Will be interesting to see who will take on the E170s - it is not exactly a sought after type. Disregarding Japanese carrier J-Air that has added 3 or 4 new-builts over the last couple of years, the last new built Embraer 170 was delivered in 2013 in 2013 to Airnorth after delivieries had started to trickle after 2009. Quite a few are now stored or have already been scrapped.
What I am, however, more interested in is whether the destinations mainly served with E170 (and not just off-peak) will survive after an upgrade to E190s - I guess DUS will be relatively safe as BACF can now lure ex Flybe customers onboard. Not sure about a place like RTM which is, IIRC, also a " mainly E170 destination".