I don't think the lore can be salvaged. It would require a whole new team but even they would lack the knowledge and passion that the OG's had, so it would be better for the new team to write something new and let all WC3 characters retire. What should at least be done to keep the game going for a few more expansions:
- The Jailer fails to destroy the universe, but he will succeed to cause major damage to Azeroth, causing the Azerothians to plan an escape to another planet
- The Jailer gets imprisoned again and will become a much better written villain for the future
- Most major lore characters will have their arcs ended, either dead or settle somewhere in peace
- New lore characters will be made, representing races that don't even have many characters at all (looking at the Forsaken who don't have anyone but Voss)
- The Alliance and Horde are no more. All races will have a clean slate to find new allies and everyone will at least be neutral with each other