Well, the Dornier 228NG is more or less built to order - they have sold roughly a dozen over almost a decade. This will not rescue regional flying.
Aren't all commercial airliners built to order?
The Do228 and the DHC6 are not prime examples, prime examples might be the 30 something seaters such as the Jetstream, SF340, Do328, the early DHC8(s) and any others that I can't think of immediately.
I read recently that someone criticised Loganair for operating a 37 year old Twotter, a local airline in my location has just started a service to my local airport operating two 31 year old BAe146-100's, these are just two examples of older aircraft types that are still in service although nearing the end of their service lives.
Similarly there are plenty of aged 30 something seaters still in service, just look at Eastern and Loganair as two examples, when these types come to the end of their service lives further route networks will be lost, in addition to those already lost, unless someone starts manufacturing such types again and apparently a company in Turkey has decided to do just that.