Jamesair, Air Wales are still operating the Plymouth - Cardiff - Newcastle route and bookings are still being taken beyond January on their website.
Air Wales are ending the Plymouth - Dublin route from 4th January and moving the Cork route to Exeter. I'm sure Airsouthwest could take over the Plymouth - Cork route as it has been running for many years. At one time both Brymon and the old Air South West (with Bandits) operated flights from Plymouth.