I can truly sympathise with you - and I know to some extent how you are feeling. Honey isn't as possessive as Archie, but she has always taken pro-active management and some level of avoiding potential issues.
And she has, accidentally, bitten me when I tried to pick up a ball and she lunged for it. After that I felt so utterly deflated and fed-up - I don't think I even posted here about it, as I was just so demoralised that after all the work we had done, everything seemed worse than ever.
But we carried on.
And I have to say, the dog we have at the minute, is a much more pleasant dog to walk and live with. Over the last couple of years, she has calmed down a LOT - she is less stressy around other dogs (with one-or-two exceptions), she retrieves her ball to hand most of the time I ask (which I don't over-do, but make sure I do a couple of times a walk) - and most notably, she lives with 2 children who leave cuddly toys around, pick up HER toys, and even occassionally hit out at her (ok, it's only the older one doing this at the minute - the younger one has grabbed fur on the odd occassion though - and to be clear, both children are actively prevented from doing this....) - when I look back at how stressed I would feel after a particularly difficult walk, it really feels like we have a different dog. I'm not complacent, and she isn't a dog I would ever trust 100%, but she is fun to walk and fun to live with!
So, yes, there is every hope that he you will not always be walking around on eggshells - but as others have said, rather than just managing the behaviour, you really need the help of a behaviourist to help address the behaviour. We had excellent advice from the behaviourists at our dog training school who suggested ways to combat the problems, and these really helped (along with excellent advice here and my own research...).
ETA - I wrote this before seeing your reply. Glad you have a plan to work on the behaviour - and, yes, in time these small steps WILL make the difference. Archie may well always have a tendency to be possessive, but with the right support it is entirely possible that you won't always be walking on egg-shells.