Thanks for all the feedback folks - good to see a discussion developing
Just to add to my original post got to thinking a TW2 neutral storyline could go (very, very broadly) something like this:
POTENTIAL SPOILERS
1. Prologue
- Geralt manages to overpowers Guard in his cell without Roche's help (uses Hex to get one guard to free him from shackles?) and escapes the dungeon. After already spying the elves in castle assault he suspects they helped the rogue Witcher somehow and follows their trail along the river to eventually reach Flotsam. He pursues them as only link to clear his name. Trail is beset with bounty hunters etc. Perhaps some mysterious figure from League of Sorceresses offers some aid in this respect (maybe suggesting working with Triss to give Geralt some clues to follow)...
2. Flotsam
- Geralt gets somesort of temporary amnesty in the town after arriving on the scene and saving the local commander's interests from bandits (barge/wagon train or suchlike). Geralt tries to uncover what he can about King-Killer in town etc while undertaking side-quests to raise coin. Due to his own status, always at risk of being targeted by bounty-hunters, Temerian vigilantes, aggrieved Temerian soldiary etc. At same time, non-human inhabitants of Flotsam would perhaps play a greater role in aiding Geralt at this point. Again, perhaps at crucial point League contact could reveal Triss's capture and hint how to regain memory. Dandelion to play a much greater role in this chapter than existing TW2 storyline.
3. Battle
Geralt is convinced by League contact to relive the battle to regain his memory. Human/Non-human conflict going on at same time is inconsequential to this ultimately. Geralt able to undertake sidequests for coin from Henselt's camp followers in area for example or other locals near non-humans area. Other quests in chapter could come from the League contact to discover more about King-Kiler/Triss's vanishing as well as getting various quest items to undertake the battle. Indeed, maybe contact tries to get Geralt to attempt to assassinate key figures, such has Dethmold, which Geralt would have to decide about; naturally this might also really begin to raise own suspicions about the aid/real motives of the league he is receiving
4. Epilogue
Geralt finally discovers elements (including own mysterious contact)of League behind Triss's abduction/King Killer's hire in conjunction with Nilfgaardians. Battle to save Triss, clear name by confronting King-Killer and League.
Obviously all of the above is very broad, very speculative and misses a huge amount of twists/content/character interaction and whatnot but I hope it shows with some work, a more neutral TW2 storyline could be worked into the storyline