Dash-8 200 would be a waste of tooling, a 300 restart would be more likely to attract enough customers. The Dash-8 design is too big/heavy for an economical 30-40 seat airliner vs its competition, bump to its 50-70 seat market and its a much better fit. Very unlikely a 30-40 seat dash would get the 100-200 orders to make a restart viable, especially with economical modern opposition in the market like the Dornier 328 ECO around the corner in the 30-40 seat range.
Bring back the Pan Am Clipper?
Get some of those jet powered Russian flying ships. Lun class, Ekranoplan, if on a budget, the recently designed A-050 Ekranoplan might be more economical.