Norwegian CAA stated to NRK (TV) that it "...will be a long time..." before the Q400 is allowed into the air again
Wrong kind of wording, possibly a translation problem or slip of the tongue if coming from a regulator rather than a politician.
Preamble: This is a continued airworthiness issue and is allowed for in the design and original certification of the aircraft so as long as it is not in violation of its original certificate basis (wear, useage, maintenance, operation, environment etc.) then the issue is expected to be addressed under the continued airworthiness part of the regulations (identify and fix it).
If it was misidentified or an inadequate fix, then the regulator needs to hold somebody's feet to the fire long enough to get it fixed. The time frame is up to both the operator and the certificate holder, the regulator might ask for more data, but they just can't ignore data and sit on their hands as a form of punishment.
So in short, even if the manufacturer or the operator screwed up, it's up to them to set the time frame for recovery. If the regulator tries to go beyond this they might as well pull the certificate of either one or both for all products they operate or design.