You’re unlikely to encounter too many computers with this hardware. What few individuals I’ve known who have a habit of sitting on an older gaming rig almost never go beyond six or seven years between new systems and this one is at least nine years old.
That being said the graphics card is still superior to even the best Intel HD GPUs.
A 9 year old mid grade for its time graphics card, on a 7 year old CPU, with a below normal amount of RAM. If the game is playable on this hardware at the lowest graphics settings I’d consider it a success.
I think you’re totally fine making the assumption that players of your game will have newer hardware than this.