I'm not a fan of the word "forever" but I know it's a term some use so I'm rolling with it ;-)
What items do you personally buy with a view to keeping them very long-term and what items do you buy with the acknowledgement (not necessarily outright intention) that they'll probably need replaced in a couple of years? Or even which items do you buy with fashion rather than longevity in mind?
If you buy longer-term/forever clothes or accessories do you only tend to have a couple of that type of item?
I know in years gone by, say pre-1950s, people would tend to make their own clothes or buy something intending to wear it for years. I find it fascinating how attitudes around fashion and style change. Years ago I came across the entries from a newspaper or magazine competition asking newlywed women to write in and describe how they would spend £X over the course of two or three years to build up their wardrobe. Things like year 1 winter coat, hosiery, summer dress; year 2 evening dress, matching bag... I am giving terrible examples. The entries were much better thought out and more detailed than that. Anyway, the winner received the £X to do exactly that - build up the wardrobe that a new wife would "need". It was really fun to read the shortlisted entries!
On a personal level, I tend to buy gloves, hiking clothes and coats with a long-term eye. I'm working on finding better quality pyjamas so I can replace them less frequently. T-shirts and long-sleeved tops I always presume will need replaced at some point but I wear them until they are well and truly done. Partly I think that is because of garment construction and partly I think it is fun to change up clothing and feel a bit expressive so I do that through tops.