Perhaps, toojaded, but you can't compare apples and oranges. Regional Jets, no matter how cost effective cannot completely replace 717s, just like 717s cannot completely replace 146s.
717s seat 115-117.
146s seat up to 84 or so.
RJs of any variety seat no more than about 60-70 (up to 80?).
An accountant looking at replacing 717s with regional jets on a one for one basis would lose anywhere between 35 and 50 seats per flight and in the language of any financial practitioner, this makes no sense.
A more likely outcome is the ultimate retirement of the 146 fleet, a gradual increase in 717 numbers up to a critical mass of perhaps 20-30 (maybe more, you never know
) and the introduction of a fleet of regional jets for routes which would justify them. Dash-8s remain largely unaffected, perhaps with a small increase in fleet size.
Bear in mind too that a 717 is not too much smaller than a 733.
My personal opinion, for what it is worth.
Allegedly.