The Eastern/Flybe competition on Southampton/Newcastle might not be such a problem. The Flybe flight is scheduled to leave Southampton at 1045 arr Newcastle 1205 with at 1230 -1345 return.
The Eastern Southampton - Newcastle - Aberdeen 145 jet flts are aimed squarely at the business market with business timings in each direction, with point to point and transit passengers. There could be room for both. The summer timetable is the one to watch