He's utilised as an almost pure attacking threat by Forest, he's often left furthest forward to begin the counter
Playing slightly deeper on the wing as you're playing Liverpool is also completely different to playing in the midfield as Wilson did against Austria. It would be a huge call to drop Wilson for Johnson.
Johnson for James is more doable, but I think James' pace and work rate is invaluable. Johnson is definitely the first player I'd look to bring on if we need a goal though